Motor and rotor

ABSTRACT

A motor includes a rotor and a stator. The rotor includes a first rotor core including a plurality of first claw-like magnetic poles, a second rotor core including a plurality of second claw-like magnetic poles, and a magnetic field magnet arranged between the first and second rotor cores. The first and second claw-like magnetic poles are alternately arranged in a circumferential direction. The magnetic field magnet causes the first and second claw-like magnetic poles to function as magnetic poles different from each other. The stator includes a first stator core including a plurality of first claw-like magnetic poles, a second stator core including a plurality of second claw-like magnetic poles, and a coil section arranged between the first and second stator cores. The stator is configured to cause the first and second claw-like magnetic poles of the stator to function as magnetic poles different from each other and switch polarities of the magnetic poles on the basis of energization to the coil section. At least ones of the claw-like magnetic poles of the rotor and the claw-like magnetic poles of the stator are formed in a shape in which circumferential centers of distal end portions are shifted in the circumferential direction with respect to circumferential centers of proximal end portions.

RELATED APPLICATION

This application is a division of application Ser. No. 14/490,016 filedSep. 18, 2014, which claims the benefit of Japanese Application No.2013196583 filed Sep. 24, 2013, Japanese Application No. 2013229456filed Nov. 5, 2013, Japanese Application No. 2013233363 filed Nov. 11,2013, Japanese Application No. 2013244076 filed Nov. 26, 2013, andJapanese Application No. 2014026843 filed Feb. 14, 2014, each of whichis hereby fully incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a motor and a rotor.

DESCRIPTION OF THE RELATED ART

Japanese Utility Model Publication No. H5-43749 describes, as a rotorused in a motor, a rotor of a Lundell type structure of a so-calledpermanent magnetic field. The rotor includes rotor cores and a magneticfield magnet. The rotor cores respectively includes a plurality ofclaw-like magnetic poles arranged in the circumferential direction andare combined to each other. The magnetic field magnet is arrangedbetween the rotor cores. The rotor causes the respective claw-likemagnetic poles to alternately function as different magnetic poles. Insuch a rotor of the Lundell type structure, it is possible to easilychange the number of poles of the rotor by changing the number of theclaw-like magnetic poles while forming the magnetic field magnet in thesame structure.

Incidentally, in the motor adopting the rotor, when it is attempted tochange the number of poles (the number of slots) of a stator accordingto a change in the number of poles of the rotor, for example, it isnecessary to change not only the shape of stator cores (the number ofteeth, etc.) but also a winding form and the like of a coil. Therefore,it is conceivable to form the stator in the Lundell type structure tocorrespond to the rotor of the Lundell type structure.

However, when both of the rotor and the stator are formed in the Lundelltype structure, it is not clarified how the shape of the rotor cores orthe stator cores (in particular, the shape of the claw-like magneticpoles) affects motor performance (torque and output). It is desired tovary the motor performance even under a condition in which power supplyto the stator is the same.

SUMMARY OF THE INVENTION

It is an objective of the present invention to provide a motor and arotor that is possible to vary the motor performance even if the powersupply to the stator is the same.

To achieve forgoing objective, a first aspect of the present inventionis a motor including a rotor and a stator. The rotor including: a firstrotor core including a plurality of first claw-like magnetic polesprojecting in an axial direction; a second rotor core including aplurality of second claw-like magnetic poles projecting in the axialdirection; and a magnetic field magnet arranged between the first andsecond rotor cores in the axial direction. The first and secondclaw-like magnetic poles are alternately arranged in a circumferentialdirection. The magnetic field magnet causes the first and secondclaw-like magnetic poles to function as magnetic poles different fromeach other. The stator including: a first stator core including aplurality of first claw-like magnetic poles projecting in the axialdirection; a second stator core including a plurality of secondclaw-like magnetic poles projecting in the axial direction; and a coilsection arranged between the first and second stator cores and woundaround in the circumferential direction. The first and second claw-likemagnetic poles of the stator are alternately arranged in thecircumferential direction and are opposed to the first and secondclaw-like magnetic poles of the rotor. The stator is configured to causethe first and second claw-like magnetic poles of the stator to functionas magnetic poles different from each other and switch polarities of themagnetic poles on the basis of energization to the coil section. Atleast ones of the claw-like magnetic poles of the rotor and theclaw-like magnetic poles of the stator are formed in a shape in whichcircumferential centers of distal end portions are shifted in thecircumferential direction with respect to circumferential centers ofproximal end portions.

A second aspect of the present invention is a motor including a rotorand a stator. The rotor includes: a first rotor core including aplurality of first rotor side claw-like magnetic poles projecting in anaxial direction; a second rotor core including a plurality of secondrotor side claw-like magnetic poles projecting in the axial direction;and a magnetic field magnet arranged between the first and second rotorcores in the axial direction. The first and second rotor side claw-likemagnetic poles are alternately arranged in a circumferential direction.The magnetic field magnet causes the first and second rotor sideclaw-like magnetic poles to function as magnetic poles different fromeach other. The stator includes: a first stator core including aplurality of first stator side claw-like magnetic poles projecting inthe axial direction; a second stator core including a plurality ofsecond stator side claw-like magnetic poles projecting in the axialdirection; and a coil section arranged between the first and secondstator cores and wound around in the circumferential direction. Thefirst and second stator side claw-like magnetic poles are alternatelyarranged in the circumferential direction and are opposed to the firstand second rotor side claw-like magnetic poles. The stator is configuredto cause the first and second stator side claw-like magnetic poles tofunction as magnetic poles different from each other and switchpolarities of the magnetic poles on the basis of energization to thecoil section. The first and second rotor cores include a plurality ofextending sections extending in a radial direction from base sectionsthat sandwich the magnetic field magnet in the axial direction. Thefirst rotor side claw-like magnetic poles are provided at radiallydistal end portions of the extending sections of the first rotor core.The second rotor side claw-like magnetic poles are provided at radiallydistal end portions of the extending sections of the second rotor core.The first and second stator cores include a plurality of extendingsections extending in the radial direction from base sections. The firststator side claw-like magnetic poles are provided at radially distal endportions of the extending sections of the first stator core. The secondstator side claw-like magnetic poles are provided at radially distal endportions of the extending sections of the second stator cores. At leastone of the extending sections of the rotor and the extending sections ofthe stator are formed in a shape in which circumferential centers of theradially distal end portions are shifted in the circumferentialdirection with respect to circumferential centers of radially proximalend portions.

A third aspect of the present invention is a motor including singlemotor sections in three stages arranged in order of a first stage, asecond stage, and a third stage in an axial direction. Each of thesingle motor sections includes a rotor section and a stator section. Therotor section includes: a first rotor core including a plurality ofclaw-like magnetic poles in a circumferential direction; a second rotorcore including a plurality of claw-like magnetic poles in thecircumferential direction; and a permanent magnet arranged between thefirst and second rotor cores and magnetized in the axial direction. Thestator section includes: a first stator core including a plurality ofclaw-like magnetic poles in the circumferential direction; a secondstator core including a plurality of claw-like magnetic poles in thecircumferential direction; and a winding wire arranged between the firstand second stator cores and wound around in the circumferentialdirection. In at least one of the rotor section and the stator sectionin the single motor section of the second stage, the plurality ofclaw-like magnetic poles are provided at unequal intervals in thecircumferential direction.

A fourth aspect of the present invention is a motor including singlemotor sections in a plurality of stages arranged in an axial direction.Each of the single motor sections includes a rotor section and a statorsection. The rotor section includes: a first rotor core including aplurality of first rotor side claw-like magnetic poles in acircumferential direction; a second rotor core including a plurality ofsecond rotor side claw-like magnetic poles in the circumferentialdirection; and a magnetic field magnet arranged between the first andsecond rotor cores assembled to each other. The rotor section causes thefirst and second rotor side claw-like magnetic poles to alternatelyfunction as different magnetic poles. The stator section includes: afirst stator core including a plurality of first stator side claw-likemagnetic poles in the circumferential direction; a second stator coreincluding a plurality of second stator side claw-like magnetic poles inthe circumferential direction; and a coil section arranged between thefirst and second stator cores assembled to each other. The statorsection is capable of switching polarities of the first and secondstator side claw-like magnetic poles on the basis of energization to thecoil section. The single motor sections in the plurality of stagesinclude (n+1) single motor sections for a U phase, n single motorsections for a V phase, and n single motor sections for a W phase. Thesingle motor sections for the U phase are arranged in stages located ataxial two ends.

A fifth aspect of the present invention is a rotor including: a magneticfield magnet magnetized in an axial direction; a first rotor core; and asecond rotor core. The first rotor core includes: a first rotor corebase arranged on one side in the axial direction of the magnetic fieldmagnet; and a plurality of first claw-like magnetic poles located atequal intervals in an outer circumferential section of the first rotorcore base and respectively bent to extend to the magnetic field magnetside in the axial direction. The second rotor core includes: a secondrotor core base arranged on the other side in the axial direction of themagnetic field magnet; and a plurality of second claw-like magneticpoles located at equal intervals in an outer circumferential section ofthe second rotor core base and respectively bent to extend to themagnetic field magnet side in the axial direction. The second claw-likemagnetic poles are respectively arranged between corresponding ones ofthe first claw-like magnetic poles of the first rotor core. The magneticfield magnet causes the first claw-like magnetic poles to function asfirst magnetic poles and causes the second claw-like magnetic poles tofunction as second magnetic poles. The first claw-like magnetic poles ofthe first rotor core are coupled to each other by a ring-like firstannular auxiliary magnet including a plurality of first magnet sectionsthat control leakage fluxes from the first claw-like magnetic poles tothe second claw-like magnetic poles adjacent thereto in thecircumferential direction. The second claw-like magnetic poles of thesecond rotor core are coupled to each other by a ring-like secondannular auxiliary magnet including a plurality of second magnet sectionsthat control leakage fluxes from the second claw-like magnetic poles tothe first claw-like magnetic poles adjacent thereto in thecircumferential direction.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with objects and advantages thereof, may best beunderstood by reference to the following description of the presentlypreferred embodiments together with the accompanying drawings in which:

FIG. 1 is a perspective view of a brushless motor according to a firstembodiment of the present invention;

FIG. 2 is a perspective view of a rotor shown in FIG. 1;

FIG. 3A is a plan view partially showing a first rotor core;

FIG. 3B is a side view showing a first rotor side claw-like magneticpole;

FIG. 4 is an exploded perspective view of a rotor section;

FIG. 5 is a sectional perspective view of a stator;

FIG. 6 is an exploded perspective view of a stator section;

FIG. 7 is a schematic diagram showing first and second rotor sideclaw-like magnetic poles in development;

FIG. 8 is a schematic diagram showing first and second stator sideclaw-like magnetic poles in development;

FIG. 9A is a graph showing comparison of torque in a configuration inthe first embodiment and torque in a conventional configuration;

FIG. 9B is a graph showing comparison of an output in the configurationin the first embodiment and the output in the conventionalconfiguration;

FIG. 10 is a schematic diagram showing first and second rotor sideclaw-like magnetic poles of another example of the first embodiment indevelopment;

FIG. 11 is a schematic diagram showing first and second rotor sideclaw-like magnetic poles of still another example of the firstembodiment in development;

FIG. 12 is a schematic diagram showing first and second rotor sideclaw-like magnetic poles of still another example of the firstembodiment in development;

FIG. 13A is a graph showing torques in various patterns in which theshapes of claw-like magnetic poles are different;

FIG. 13B is a graph showing outputs in the various patterns shown inFIG. 13A;

FIG. 14 is a perspective view of a rotor in still another example of thefirst embodiment;

FIG. 15A is a plan view partially showing a first rotor core in therotor of the example shown in FIG. 14;

FIG. 15B is a side view showing a first rotor side claw-like magneticpole of the example shown in FIG. 14;

FIG. 16 is a perspective view of a stator in still another example ofthe first embodiment;

FIG. 17A is a plan view partially showing a first stator core of thestator of the example shown in FIG. 16;

FIG. 17B is a side view showing a first stator side claw-like magneticpole of the stator of the example shown in FIG. 16;

FIG. 18A is a graph showing torques in various patterns in which shapesof extending sections are different.

FIG. 18B is a graph showing outputs in the various patterns showing inFIG. 18A;

FIG. 19 is a perspective view of a motor according to a secondembodiment of the present invention;

FIG. 20 a perspective view of a rotor according to the secondembodiment;

FIG. 21 is an exploded perspective view of a rotor section in the secondembodiment;

FIG. 22 is a perspective view of U-phase and W-phase rotor sections inthe second embodiment;

FIG. 23 is a perspective view of a V-phase rotor section in the secondembodiment;

FIG. 24 is a schematic diagram for explaining a positional relationbetween first and second rotor side claw-like magnetic poles in thesecond embodiment;

FIG. 25 is a schematic diagram for explaining a positional relationbetween first and second rotor side claw-like magnetic poles of areference configuration;

FIG. 26 is a sectional perspective view of a stator in the secondembodiment;

FIG. 27 is an exploded perspective view of a stator section in thesecond embodiment;

FIG. 28 is a perspective view of U-phase and W-phase stator sections inthe second embodiment;

FIG. 29 is a perspective view of a V-phase stator section in the secondembodiment;

FIG. 30 is a schematic diagram for explaining a positional relationbetween first and second stator side claw-like magnetic poles in thesecond embodiment;

FIG. 31 is a schematic diagram for explaining a positional relationbetween first and second stator side claw-like magnetic poles of thereference configuration;

FIG. 32 is a graph showing comparison of average torques in the secondembodiment and the reference configuration;

FIG. 33 is a schematic diagram for explaining a positional relationbetween first and second rotor side claw-like magnetic poles of anotherexample of the second embodiment;

FIG. 34 is a schematic diagram for explaining a positional relationbetween first and second stator side claw-like magnetic poles of stillanother example of the second embodiment;

FIG. 35 is a graph showing average torques in various patterns in whichthe arrangement of claw-like magnetic poles is different;

FIG. 36 is a perspective view of a motor according to a third embodimentof the present invention;

FIG. 37 is a perspective view of a rotor according to the thirdembodiment;

FIG. 38 is an exploded perspective view of a rotor section in the thirdembodiment;

FIG. 39 is a perspective view partially showing a stator in the thirdembodiment;

FIG. 40 is an exploded perspective view of a stator section in the thirdembodiment;

FIG. 41A is a graph showing induced voltages in respective phases in aconventional motor;

FIG. 41B is a graph showing induced voltages in respective phases in themotor according to the third embodiment;

FIG. 42 is a perspective view of a motor according to a fourthembodiment of the present invention;

FIG. 43 is a front view of the motor according to the fourth embodimentviewed from the axial direction;

FIG. 44 is a combined sectional view taken along line A-O-A in FIG. 43;

FIG. 45 is a perspective view or a rotor according to the fourthembodiment;

FIG. 46 is an exploded perspective view of the rotor according to thefourth embodiment;

FIG. 47 is a perspective view of first and second annular auxiliarymagnets in the fourth embodiment;

FIG. 48 is a main part enlarged sectional perspective view of the rotoraccording to the fourth embodiment;

FIG. 49 is a perspective view of a stator in the fourth embodiment;

FIG. 50 is an exploded perspective view of the stator according to thefourth embodiment;

FIG. 51 is an induced voltage characteristic curve diagram forexplaining an output characteristic of the motor according to the fourthembodiment;

FIG. 52 is an explanatory diagram for explaining rotation detection of amotor in which the first annular auxiliary magnet in the fourthembodiment is used;

FIG. 53 is a detected waveform chart of a leakage flux detected by amagnetic detector;

FIG. 54 is a main part enlarged sectional perspective view of a rotoraccording to a fifth embodiment of the present invention;

FIG. 55 is an induced voltage characteristic curve diagram forexplaining an output characteristic of a motor according to the fifthembodiment;

FIG. 56 is an explanatory diagram for explaining rotation detection of amotor in which a first annular auxiliary magnet in the fifth embodimentis used;

FIG. 57 is a detected waveform chart of a leakage flux detected by amagnetic detector;

FIG. 58 is a main part enlarged sectional perspective view of a rotoraccording to a sixth embodiment of the present invention;

FIG. 59 is an induced voltage characteristic curved diagram forexplaining an output characteristic of a motor according to the sixthembodiment;

FIG. 60 is a main part enlarged sectional perspective view of a rotoraccording to a seventh embodiment of the present invention;

FIG. 61 is an induced voltage characteristic curve diagram forexplaining an output characteristic of a motor according to the seventhembodiment;

FIG. 62 is an explanatory diagram for explaining rotation detection of amotor in which a first annular auxiliary magnet in the seventhembodiment is used;

FIG. 63 is a detected waveform chart of a leakage flux detected by amagnetic detector;

FIG. 64 is a perspective view of a three-phase brushless motor forexplaining another example of the fourth to seventh embodiments;

FIG. 65 is a front view of a three-phase rotor viewed from the radialdirection; and

FIG. 66 is a sectional view of a three-phase stator.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A motor according to a first embodiment is explained below.

As shown in FIG. 1, a brushless motor 10 according to this embodimentincludes a rotor 12 including a rotating shaft 11 and an annular stator13 arranged on the outer side of the rotor 12 and firmly fixed to amotor housing (not shown in the figure).

Configuration of the Rotor

As shown in FIG. 2, the rotor 12 includes rotor sections 14 u, 14 v, and14 w of three phases (a U phase, a V phase, and a W phase) stacked inthe axial direction. The rotor sections 14 u, 14 v, and 14 w havesubstantially the same configurations one another and are configured byfirst and second rotor cores 21 and 22 and magnetic field magnets 23sandwiched by the first and second rotor cores 21 and 22.

As shown in FIGS. 2 and 4, the first rotor core 21 includes a firstrotor core base 24 formed in a substantially disk shape. The first rotorcore base 24 includes a disk section 24 b having a through-hole 24 a,through which the rotating shaft 11 is inserted and fixed, in a radialcenter section and a plurality of extending sections 24 c extending fromthe outer circumferential edge of the disk section 24 b to the radialouter side. In this embodiment, twelve extending sections 24 c areprovided at equal intervals (30 degree intervals) in the circumferentialdirection.

As shown in FIG. 3A, the extending section 24 c is formed in atrapezoidal shape smaller in width toward the radial outer side whenviewed from the axial direction. Concerning the shape of the extendingsection 24 c, more specifically, a circumferential center line L (astraight line passing a circumferential center P1 at the radiallyproximal end portion and a circumferential center P2 at the radiallydistal end portion) of the extending section 24 c is orthogonal to theaxis of the rotating shaft 11. The extending section 24 c is formed in ashape line-symmetrical to the circumferential center line L when viewedfrom the axial direction of the extending section 24 c.

The first rotor core 21 integrally includes first rotor side claw-likemagnetic poles 25 that project to one side in the axial direction fromthe radially distal end portions (the outer circumferential side endportions) of the extending sections 24 c. Note that the first rotor sideclaw-like magnetic pole 25 may be formed by bending the extendingsections 24 c at a right angle or may be molded integrally with theextending sections 24 c by casting.

As shown in FIG. 3B, the first rotor side claw-like magnetic pole 25 isformed in a symmetrical trapezoidal shape when viewed from the radialdirection (the front). More specifically, the first rotor side claw-likemagnetic pole 25 is formed in a trapezoidal shape, the circumferentialwidth of the axially proximal end portion of which is formed equal tothe circumferential width of the radially distal end portion (the outercircumferential side end portion) of the extending section 24 c and issmaller toward the axially distal end side. The first rotor sideclaw-like magnetic pole 25 has circumferential two faces that are formedin flat surfaces nonparallel to each other. Further, in the first rotorside claw-like magnetic pole 25, a straight line L0 passing acircumferential center X1 of the axially proximal end portion and acircumferential center X2 of the axially distal end portion inclineswith respect to the axial direction.

As shown in FIG. 4, a second rotor core 22 includes a configurationsubstantially the same as the configuration of the first rotor core 21and includes a second rotor core base 26 and second rotor side claw-likemagnetic poles 27. A disk section 26 b (a through-hole 26 a) andextending sections 26 c of the second rotor core base 26 respectivelyhave shapes same as the shapes of the disk section 24 b (thethrough-hole 24 a) and the extending sections 24 c of the first rotorcore base 24.

As shown in FIG. 2, in an assembled state, the second rotor core base 26is arranged in parallel to the first rotor core base 24. The magneticfield magnet 23 is arranged between the core bases 24 and 26. Theextending sections 24 c and 26 c of the core bases 24 and 26 arealternately lined in the circumferential direction when viewed from theaxial direction and are arranged at equal intervals (in this embodiment,15 degree intervals) in the circumferential direction. The first andsecond rotor side claw-like magnetic poles 25 and 27 are arranged to bealternately lined in the circumferential direction and are configured toproject in opposite directions each other. In other words, the secondrotor side claw-like magnetic poles 27 are arranged betweencorresponding ones of the first rotor side claw-like magnetic poles 25.

Note that the axial length of the first rotor side claw-like magneticpole 25 is set such that the distal end face of the first rotor sideclaw-like magnetic pole 25 is flush with an opposed surface 26 d (anaxially inner side surface) of the second rotor core base 26. Similarly,the axial length of the second rotor side claw-like magnetic pole 27 isset such that the distal end face of the second rotor side claw-likemagnetic pole 27 is flush with an opposed surface 24 d (an axially innerside surface) of the first rotor core base 24.

The second rotor side claw-like magnetic pole 27 is formed in asymmetrical trapezoidal shape when viewed from the radial direction (thefront). More specifically, the second rotor side claw-like magnetic pole27 is formed in a trapezoidal shape, the circumferential width of theaxially proximal end portion of which is equal to the circumferentialwidth of the radially distal end portion (the outer circumferential sideend portion) of the extending section 26 c and is smaller toward theaxially distal end side. The circumferential two end faces of the secondrotor side claw-like magnetic pole 27 are formed in flat surfacesnonparallel to each other.

As shown in FIG. 4, the magnetic field magnet 23 is, for example, adisk-like permanent magnet formed by a ferrite magnet. A through-hole 23a, through which the rotating shaft 11 is inserted, is formed in thecenter position of the magnetic field magnet 23. One end face 23 b ofthe magnetic field magnet 23 is in contact with the opposed surface 24 dof the first rotor core base 24. The other end face 23 c of the magneticfield magnet 23 is in contact with the opposed surface 26 d of thesecond rotor core base 26. The magnetic field magnet 23 is sandwichedand fixed in the axial direction between the first rotor core base 24and the second rotor core base 26. Note that the outer diameter of themagnetic field magnet 23 is set the same as the outer diameter of thedisk sections 24 b and 26 b of the core bases 24 and 26.

The magnetic field magnet 23 is magnetized in the axial direction to setthe first rotor core base 24 side as an N pole and set the second rotorcore base 26 side as an S pole. Therefore, the first rotor sideclaw-like magnetic poles 25 of the first rotor core 21 are caused tofunction as N poles (first magnetic poles) by the magnetic field magnet23. The second rotor side claw-like magnetic poles 27 of the secondrotor core 22 are caused to function as S poles (second magnetic poles)by the magnetic field magnet 23.

In the rotor sections 14 u, 14 v, and 14 w formed in a so-called Lundelltype structure including the magnetic field magnets 23 as explainedabove, the first rotor side claw-like magnetic poles 25 functioning asthe N poles and the second rotor side claw-like magnetic poles 27functioning as the S poles are alternately arranged in thecircumferential direction. Each of the rotor sections 14 u, 14 v, and 14w is configured by twenty-four poles (twelve pole pairs).

As shown in FIG. 2, the rotor sections 14 u, 14 v, and 14 w are stackedin the axial direction to configure the rotor 12. Note that the rotorsections 14 u, 14 v, and 14 w in the respective phases are referred toas U-phase rotor section 14 u, V-phase rotor section 14 v, and W-phaserotor section 14 w in order from the top in FIG. 2.

The rotor sections 14 u, 14 v, and 14 w in the respective phases arestacked with the phases shifted 60 degrees in an electrical angle (5degrees in a mechanical angle) from one another. More specifically, theV-phase rotor section 14 v is arranged to be shifted 60 degrees in thephase in the electrical angle in the counterclockwise direction withrespect to the U-phase rotor section 14 u. The W-phase rotor section 14w is arranged to be shifted 60 degrees in the phase in the electricalangle in the counterclockwise direction with respect to the V-phaserotor section 14 v.

The U-phase and W-phase rotor sections 14 u and 14 w are stacked withthe first rotor core 21 facing up. The V-phase rotor section 14 v isstacked with the second rotor core 22 facing up. That is, magnetizationdirections of the magnetic field magnets 23 of the U-phase and W-phaserotor sections 14 u and 14 w are set in the same direction (in FIG. 2,upward). A magnetization direction of the magnetic field magnet 23 ofthe V-phase rotor section 14 v is set in a direction (in FIG. 2,downward) opposite to the magnetization direction of the magnetic fieldmagnets 23 of the U-phase and W-phase rotor sections 14 u and 14 w.

The second rotor core bases 26 of the U-phase and V-phase rotor sections14 u and 14 v are adjacent to each other in the axial direction. The Spole sides of the magnetic field magnets 23 of the U-phase and V-phaserotor sections 14 u and 14 v are configured to face each other via theadjacent second rotor core bases 26. The first rotor core bases 24 ofthe V-phase and W-phase rotor sections 14 v and 14 w are adjacent toeach other in the axial direction. The N pole sides of the magneticfield magnets 23 of the V-phase and W-phase rotor sections 14 v and 14 ware configured to face each other via the adjacent first rotor corebases 24.

Projecting directions in the axial direction of the first rotor sideclaw-like magnetic poles 25 of the U-phase and W-phase rotor sections 14u and 14 w are the same direction (in FIG. 2, downward). A projectingdirection of the first rotor side claw-like magnetic poles 25 of theV-phase rotor section 14 v is a direction (in FIG. 2, upward) oppositeto the direction.

Similarly, projecting directions in the axial direction of the secondrotor side claw-like magnetic poles 27 of the U-phase and W-phase rotorsections 14 u and 14 w are the same direction (in FIG. 2, upward). Aprojecting direction of the second rotor side claw-like magnetic poles27 of the V-phase rotor section 14 v is a direction (in FIG. 2,downward) opposite to the direction.

As shown in FIG. 7, in the rotor sections 14 u, 14 v, and 14 w, theradial outer side surface (a surface opposed to the stator 13) of thefirst rotor side claw-like magnetic pole 25 is formed as an inclinedsection 25 b, circumferential one end 25 a (a front side end in theclockwise direction) of which is formed in a linear shape extendingalong the axial direction viewed from the radial direction andcircumferential other end (a rear side end in the clockwise direction)of which is inclined to be closer to the circumferential one end 25 atoward the distal end side. That is, the first rotor side claw-likemagnetic pole 25 is formed in a shape in which the circumferentialcenter X2 of the distal end portion is shifted to one side in thecircumferential direction (in this embodiment, the clockwise direction)with respect to the circumferential center X1 of the proximal endportion (coinciding with the circumferential center P2 at the radiallydistal end portion of the extending section 24 c).

In the rotor sections 14 u, 14 v, and 14 w, the radial outer sidesurface (a surface opposed to the stator 13) of the second rotor sideclaw-like magnetic pole 27 is formed as an inclined section 27 b,circumferential one end 27 a (a front side end in the clockwisedirection) of which is formed in a linear shape extending along theaxial direction viewed from the radial direction and circumferentialother end (a rear side end in the clockwise direction) of which isinclined to be closer to the circumferential one end 27 a toward thedistal end side. Consequently, the second rotor side claw-like magneticpole 27 is formed in a shape in which a circumferential center Y2 of thedistal end portion is shifted to one side in the circumferentialdirection (in this embodiment, the clockwise direction) with respect toa circumferential center Y1 of the proximal end portion.

That is, the first and second rotor side claw-like magnetic poles 25 and27 are formed in shapes in which the circumferential centers X2 and Y2of the distal end portions thereof are shifted in the same direction(the clockwise direction). The first and second rotor side claw-likemagnetic poles 25 and 27 are configured to arrange center positions C1and C2 thereof (circumferential center positions in the axial centers ofthe claw-like magnetic poles 25 and 27) at equal intervals (in thisembodiment, 15 degree intervals) in the circumferential direction. Aninclination angle θ1 (an inclination angle with respect to the axialdirection) of the inclined section 25 b of the first rotor sideclaw-like magnetic pole 25 and an inclination angle θ2 (an inclinationangle with respect to the axial direction) of the inclined section 27 bof the second rotor side claw-like magnetic pole 27 are set equal toeach other.

Stator

As shown in FIG. 5, the stator 13 arranged on the radial outer side ofthe rotor 12 includes stator sections 30 u, 30 v, and 30 w of the threephases (the U phase, the V phase, and the W phase) stacked in the axialdirection to correspond to the rotor sections 14 u, 14 v, and 14 w. Thestator sections 30 u, 30 v, and 30 w have the same configuration and areconfigured from first and second stator cores 31 and 32 and a coilsection 33 arranged in the axial direction between the first and secondstator cores 31 and 32.

As shown in FIGS. 5 and 6, a first stator core 31 includes a ringplate-like first stator core base 34. The first stator core base 34includes a ring section 34 a formed in a ring shape in thecircumferential direction of the rotating shaft 11 and a plurality ofextending sections 34 b extending in the radial inner side from the ringsection 34 a. In this embodiment, twelve extending sections 34 b areprovided at equal intervals (30 degree intervals) in the circumferentialdirection. The extending sections 34 b are formed in a trapezoidal shapesmaller in width toward the radial inner side and line-symmetrical withrespect to the circumferential center line when viewed from the axialdirection.

The first stator core 31 integrally includes first stator side claw-likemagnetic poles 35 projecting to one side in the axial direction (in FIG.5, downward) from the radially distal end portions (the outercircumferential side end portions) of the extending sections 34 b. Notethat the first stator side claw-like magnetic poles 35 may be formed bybending the extending sections 34 b at a right angle or may be moldedintegrally with the extending sections 34 b by casting.

The first stator side claw-like magnetic pole 35 is formed in asymmetrical trapezoidal shape when viewed from the radial direction (thefront). More specifically, the first stator side claw-like magnetic pole35 is formed in a trapezoidal shape, the circumferential width of theaxially proximal end portion of which is formed equal to thecircumferential width of the radially distal end portion (the innercircumferential side end portion) of the extending section 34 b and issmaller toward the axially distal end side. The circumferential two endfaces of the first stator side claw-like magnetic pole 35 are formed inflat surfaces nonparallel to each other.

As shown in FIG. 8, the radial inner side surface (a surface opposed tothe rotor 12) of the first stator side claw-like magnetic pole 35 isformed as an inclined section 35 b, circumferential one end 35 a (a rearside end in the clockwise direction) of which is formed in a linearshape extending along the axial direction viewed from the radialdirection and circumferential other end (a front side end in theclockwise direction) of which is inclined to be closer to thecircumferential one end 35 a toward the distal end side. That is, thefirst stator side claw-like magnetic pole 35 is formed in a shape inwhich a circumferential center Z2 of the distal end portion is shiftedto one side in the circumferential direction (in this embodiment, thecounterclockwise direction) with respect to a circumferential center Z1of the proximal end portion.

As shown in FIG. 6, a second stator core 32 includes a configurationsubstantially the same as the configuration of the first stator core 31and includes a second stator core base 36 and second stator sideclaw-like magnetic poles 37. A ring section 36 a and extending sections36 b of the second stator core base 36 are formed in shapes respectivelythe same as the shapes of the ring section 34 a and the extendingsections 34 b of the first stator core base 34.

As shown in FIG. 5, the ring sections 34 a and 36 a of the stator corebases 34 and 36 are set in contact with each other in the axialdirection to configure an outer circumferential wall section of thefirst stator core 31. In a space on the inner circumferential side ofthe outer circumferential wall section, which is a space in the axialdirection between the extending sections 34 b and 36 b, a coil section33 formed in a ring shape in the circumferential direction of therotating shaft 11 is arranged.

The extending sections 34 b and 36 b of the stator core bases 34 and 36are alternately lined in the circumferential direction when viewed fromthe axial direction and are arranged at equal intervals (in thisembodiment, 15 degree intervals) in the circumferential direction. Theextending sections 34 b and 36 b are formed parallel to each other. Inthe stator sections 30 u, 30 v, and 30 w, the first and second statorside claw-like magnetic poles 35 and 37 are arranged to be alternatelylined in the circumferential direction and are configured to project inopposite directions each other. In other words, the second stator sideclaw-like magnetic poles 37 are arranged between the corresponding onesof the first stator side claw-like magnetic poles 35.

The second stator side claw-like magnetic poles 37 are formed in asymmetrical trapezoidal shape when viewed from the radial direction (thefront). More specifically, the second stator side claw-like magneticpole 37 is formed in a trapezoidal shape, the circumferential width ofthe axially proximal end portion of which is formed equal to thecircumferential width of the radially distal end portion (the outercircumferential side end portion) of the extending section 36 b and issmaller toward the axially distal end side. The circumferential two endfaces of the second stator side claw-like magnetic pole 37 are formed inflat surfaces nonparallel to each other.

As shown in FIG. 8, the radial inner side surface (a surface opposed tothe rotor 12) of the second stator side claw-like magnetic pole 37 isformed as an inclined section 37 b, circumferential one end 37 a (a rearside end in the clockwise direction) of which is formed in a linearshape extending along the axial direction viewed from the radialdirection and circumferential other end (a front side end in theclockwise direction) of which is inclined to be closer to thecircumferential one end 37 a toward the distal end side. Consequently,the second stator side claw-like magnetic pole 37 is formed in a shapein which a circumferential center T2 of the distal end portion isshifted to one side in the circumferential direction (in thisembodiment, the counterclockwise direction) with respect to acircumferential center T1 of the proximal end portion.

That is, the first and second stator side claw-like magnetic poles 35and 37 are formed in shapes in which the circumferential centers Z2 andT2 of the distal end portions thereof are shifted in the same direction(the counterclockwise direction). The first and second stator sideclaw-like magnetic poles 35 and 37 are configured such that centerpositions C3 and C4 thereof (circumferential center positions in theaxial centers of the claw-like magnetic poles 35 and 37) are arranged atequal intervals (in this embodiment, 15 degree intervals) in thecircumferential direction. An inclination angle θ3 (an inclination anglewith respect to the axial direction) of the inclined section 35 b of thefirst stator side claw-like magnetic pole 35 and an inclination angle θ4(an inclination angle with respect to the axial direction) of theinclined section 37 b of the second stator side claw-like magnetic pole37 are set equal to each other.

The stator sections 30 u, 30 v, and 30 w configured as explained aboveare formed in a so-called Lundell type (a claw pole type) structureincluding twenty-four poles that energize, with the coil section 33, thefirst and second stator side claw-like magnetic poles 35 and 37 to bedifferent magnetic poles each other at every moment.

As shown in FIG. 5, the stator sections 30 u, 30 v, and 30 w are stackedin the axial direction such that the first stator core base 34 and thesecond stator core base 36 are alternately arranged in the axialdirection. Consequently, the stator 13 is configured. Note that thestator sections 30 u, 30 v, and 30 w in the respective phases arereferred to as U-phase stator section 30 u, V-phase stator section 30 v,and W-phase stator section 30 w in order from the top in FIG. 5.

The stator sections 30 u, 30 v, and 30 w in the respective phases arestacked with the phases shifted 60 degrees in the electrical angle (5degrees in the mechanical angle) from one another. More specifically,the V-phase stator section 30 v is arranged to be shifted 60 degrees inthe phase in the electrical angle in the clockwise direction withrespect to the U-phase stator section 30 u. The W-phase stator section30 w is arranged to be shifted 60 degrees in the phase in the electricalangle in the clockwise direction with respect to the V-phase statorsection 30 v.

Consequently, a direction of inclination with respect to the axialdirection formed by the shift in the circumferential direction of therotor sections 14 u, 14 v, and 14 w in the respective phases when viewedfrom the radial direction (see FIG. 2) and a direction of inclinationwith respect to the axial direction formed by the shift in thecircumferential direction of the stator sections 30 u, 30 v, and 30 w inthe respective phases when viewed from the radial direction (see FIG. 5)are opposite directions each other on opposed surfaces of the rotor 12and the stator 13. Consequently, it is possible to cause the first andsecond rotor side claw-like magnetic poles 25 and 27 in the respectivephases to suitably follow switching of the magnetic poles of the firstand second stator side claw-like magnetic poles 35 and 37. As a result,it is possible to realize suitable rotation of the rotor 12.

Action of the brushless motor 10 configured as explained above isexplained.

When a three-phase alternating-current power supply voltage is appliedto the stator 13, a U-phase power supply voltage is applied to the coilsection 33 of the U-phase stator section 30 u, a V-phase power supplyvoltage is applied to the coil section 33 of the V-phase stator section30 v, and a W-phase power supply voltage is applied to the coil section33 of the W-phase stator section 30 w. Consequently, a rotating magneticfield is generated in the stator 13 and the rotor 12 is driven torotate.

It is assumed that the rotor 12 shown in FIG. 2 rotatescounterclockwise. In this case, as shown in FIGS. 7 and 8, the inclinedsections 25 b and 27 b are located on the rotor rotating direction frontside of the rotor side claw-like magnetic poles 25 and 27. The inclinedsections 35 b and 37 b are located on the rotor rotating direction rearside of the stator side claw-like magnetic poles 35 and 37. That is, therotor side claw-like magnetic poles 25 and 27 are formed in anasymmetrical shape in which the circumferential centers X2 and Y2 of thedistal end portions are shifted in a counter rotating direction of therotor 12 with respect to the circumferential centers X1 and Y1 of theproximal end portions. The stator side claw-like magnetic poles 35 and37 are formed in an asymmetrical shape in which the circumferentialcenters Z2 and T2 of the distal end portions are shifted in the rotatingdirection of the rotor 12 with respect to the circumferential centers Z1and T1 of the proximal end portions.

When this configuration is compared with the conventional configurationin which the claw-like magnetic poles of the rotor and the stator havethe symmetrical shape when viewed from the radial direction, as shown inFIGS. 9A and 9B, in this embodiment, torque is improved to 120% or moreand an output is improved to 130% or more with respect to theconventional configuration.

During the rotor rotation, magnet torque by the magnetic field magnets23 acts as positive torque (rotation torque) in both attraction andrepulsion. However, reluctance torque acts as positive torque inattraction and acts as negative torque in repulsion. In the conventionalconfiguration, an attraction component and a repulsion component of thereluctance torque are offset. The reluctance torque substantially doesnot contribute to the rotation torque.

On the other hand, in this embodiment, the rotor side claw-like magneticpoles 25 and 27 are formed in an asymmetrical shape in which the distalend sides are shifted in the counter rotating direction of the rotor 12.The stator side claw-like magnetic poles 35 and 37 are formed in anasymmetrical shape in which the distal end sides are shifted in therotating direction of the rotor 12. Consequently, the repulsioncomponent of the reluctance torque acting as the negative torque issuppressed. As a result, the attraction component of the reluctancetorque acting as the positive torque remains. Therefore, the torque andthe output are improved.

Characteristic advantages of the first embodiment are explained.

(1) The rotor side claw-like magnetic poles 25 and 27 and the statorside claw-like magnetic poles 35 and 37 are formed in shapes(asymmetrical shapes) in which the circumferential centers of the distalend portions are shifted in the circumferential direction with respectto the circumferential centers of the proximal end portions.Consequently, it is possible to vary the reluctance torque according tothe shape of the claw-like magnetic poles 25, 27, 35, and 37. As aresult, it is possible to vary motor performance (torque and an output)even if power supply to the stator 13 is the same.

(2) The rotor side claw-like magnetic poles 25 and 27 are formed in anasymmetrical shape in which the distal end sides are shifted in thecounter rotating direction of the rotor 12. The stator side claw-likemagnetic poles 35 and 37 are formed in an asymmetrical shape in whichthe distal end sides are shifted in the rotating direction of the rotor12. Consequently, it is possible to suppress the repulsion component ofthe reluctance torque acting as the negative torque. As a result, it ispossible to contribute to improvement of the torque and the output.

Note that the first embodiment may be changed as explained below.

A shift direction (a shifting direction) of the distal end sides of theclaw-like magnetic poles 25, 27, 35, and 37 is not limited to theembodiment.

For example, as shown in FIG. 10, a distal end shift direction of thefirst rotor side claw-like magnetic pole 25 and a distal end shiftdirection of the second rotor side claw-like magnetic pole 27 may be setopposite to each other. Note that, in FIG. 10, an example is shown inwhich the distal end shift direction of the first rotor side claw-likemagnetic pole 25 is set in the counter rotating direction of the rotor12 and the distal end shift direction of the second rotor side claw-likemagnetic pole 27 is set in the rotating direction of the rotor 12.Consequently, the inclined sections 25 b and 27 b of the rotor sideclaw-like magnetic poles 25 and 27 are opposed to each other in thecircumferential direction.

On the stator 13 side, similarly, a distal end shift direction of thefirst stator side claw-like magnetic pole 35 and a distal end shiftdirection of the second stator side claw-like magnetic pole 37 may beset in opposite directions each other. The inclined sections 35 b and 37b of the stator side claw-like magnetic poles 35 and 37 may be opposedto each other in the circumferential direction.

In FIGS. 13A and 13B, torques and outputs in various patterns in whichthe distal end shift directions of the claw-like magnetic poles 25, 27,35, and 37 on the rotor 12 side and the stator 13 side are different arerespectively shown. In FIGS. 13A and 13B, a configuration in which thedistal end shift direction is the counter rotating direction of therotor 12 is represented as pattern “A”, a configuration in which thedistal end shift direction is the rotating direction of the rotor 12 isrepresented as pattern “B”, a configuration in which the distal endshift direction is opposite in the first and second rotor side claw-likemagnetic poles 25 and 27 (or the first and second stator side claw-likemagnetic poles 35 and 37) (see FIG. 10) is represented as pattern “C”,and the conventional configuration (the symmetrical shape) isrepresented as pattern “D”. In FIGS. 13A and 13B, the torque or theoutput of a configuration in which the patterns of the rotor and thestator side are “D/D” (the conventional configuration) are set to 100%.

As shown in FIG. 13A, among combinations of the patterns, the torque isthe highest in a configuration in which the patterns of the rotor andthe stator side are “A/B” (the configuration in the embodiment). Thetorque decreases in “D/B”, “A/C”, “D/C”, “C/B”, “A/D”, “C/C”, and “B/B”in order from the pattern. However, the torques in the patterns arehigher than 100%. That is, by setting the claw-like magnetic poles 25,27, 35, and 37 of the rotor and the stator side in these patterns, it ispossible to improve the torque.

The torque is equal to or lower than 100% in a configuration in whichthe patterns of the rotor and the stator side are “C/D”. The torquedecreases in “B/C”, “A/A”, “D/A”, “B/D”, “C/A”, and “B/A” in order fromthe pattern. That is, by setting the claw-like magnetic poles 25, 27,35, and 37 of the rotor and the stator side in these patterns, it ispossible to provide a motor that can obtain low torque.

In the embodiment, when the rotor 12 shown in FIG. 2 rotatescounterclockwise (regularly rotates), the patterns of the rotor and thestator side are “A/B”. However, when the rotor 12 rotates clockwise(reversely rotates), the patterns of the rotor and the stator side are“B/A”. Consequently, when the rotor 12 is regularly and reverselyrotated with the same power supply to the stator 13, it is possible toreduce the torque in the reverse rotation with respect to the torque inthe regular rotation.

When two operations having different loads are respectively performed bythe regular and reverse rotations of the rotor 12, it is desirable thatthe operation having a larger load is performed by the regular rotationand the operation having a smaller load is performed by the reverserotation. For example, in a power window device for a vehicle, loads ofan opening motion and a closing motion are different because of the ownweight of glass. Therefore, if the regular rotation of the rotor 12 isallocated to the closing motion of the glass and the reverse rotation ofthe rotor 12 is allocated to the opening motion of the glass, it ispossible to realize suitable opening and closing motions of the glasswithout changing the magnitude of the power supply to the stator 13.

As shown in FIG. 13B, in configurations in which the patterns of therotor and the stator side are “A/B”, “D/B”, “A/C”, “D/C”, “C/B”, “A/D”,“C/C”, and “B/B”, the output is higher than 100%. That is, by settingthe claw-like magnetic poles 25, 27, 35, and 37 of the rotor and thestator side in these patterns, it is possible to improve the output. Theoutput is the highest in the configuration in which the patterns of therotor and the stator side are “A/B” (the configuration in theembodiment).

In configurations in which the patterns of the rotor and the stator sideare “C/D”, “B/C”, “A/A”, “D/A”, “B/D”, “C/A”, and “B/A”, the output isequal to or lower than 100%. That is, by setting the claw-like magneticpoles 25, 27, 35, and 37 of the rotor and the stator side in thesepatterns, it is possible to provide a motor that can obtain a lowoutput.

As shown in FIGS. 13A and 13B, when the pattern of the stator is “B”,that is, the distal end shift directions of the first and second statorside claw-like magnetic poles 35 and 37 are the rotating direction ofthe rotor 12, it is possible to improve the torque and the outputirrespective of the pattern of the rotor.

In the embodiment, the inclination angle θ1 of the inclined section 25 bof the first rotor side claw-like magnetic pole 25 and the inclinationangle θ2 of the inclined section 27 b of the second rotor side claw-likemagnetic pole 27 are set equal to each other. However, the inclinationangles θ1 and 02 are not limited to this. As shown in FIG. 11, theinclination angles θ1 and θ2 may be set different from each other. In anexample shown in FIG. 11, the inclination angle θ2 is set smaller thanthe inclination angle θ1. However, conversely, the inclination angle θ1may be set smaller than the inclination angle θ2. On the stator 13 side,similarly, the inclination angle θ3 of the inclined section 35 b of thefirst stator side claw-like magnetic pole 35 and the inclination angleθ4 of the inclined section 37 b of the second stator side claw-likemagnetic pole 37 may be set different from each other.

In the embodiment, the first and second rotor side claw-like magneticpoles 25 and 27 are configured such that the center positions C1 and C2thereof are arranged at the equal intervals in the circumferentialdirection. However, the first and second rotor side claw-like magneticpoles 25 and 27 are not limited to this. As shown in FIG. 12, the firstand second rotor side claw-like magnetic poles 25 and 27 may beconfigured such that the center positions C1 and C2 are arranged atunequal intervals in the circumferential direction. On the stator 13side, similarly, the first and second stator side claw-like magneticpoles 35 and 37 may be configured such that the center positions C3 andC4 thereof are arranged at unequal intervals in the circumferentialdirection.

In the embodiment, the circumferential ends (the circumferential oneends 25 a, 27 a, 35 a, and 37 a) on the opposite side of the inclinedsections 25 b, 27 b, 35 b, and 37 b in the claw-like magnetic poles 25,27, 35, and 37 are formed in the linear shape extending along the axialdirection of the rotating shaft 11. However, the circumferential endsare not limited to this and may be inclined with respect to the axialdirection of the rotating shaft 11. In the embodiment, the claw-likemagnetic poles 25, 27, 35, and 37 are formed in the trapezoidal shape asviewed in the radial direction. However, besides the trapezoidal shape,the claw-like magnetic poles 25, 27, 35, and 37 may be formed in, forexample, a triangular shape, a semicircular shape, a semiellipticalshape, or a polygonal shape.

The number of the claw-like magnetic poles 25, 27, 35, and 37 (thenumber of magnetic poles) is not limited to the embodiment and may bechanged as appropriate according to a configuration.

The first and second rotor cores 21 and 22 in the embodiment areconfigured such that the distal ends of the first and second rotor sideclaw-like magnetic poles 25 and 27 are shifted in the circumferentialdirection. However, the first and second rotor cores 21 and 22 are notlimited to this and may be configured such that the radially distal endsof the extending sections 24 c and 26 c are shifted in thecircumferential direction.

For example, as shown in FIGS. 14 and 15A and 15B, the extendingsections 24 c and 26 c of the first and second rotor core bases 24 and26 are formed in shapes in which the radially distal end portions (theouter circumferential side end portions) thereof are shifted to one sidein the circumferential direction (in FIG. 14, the clockwise direction).

The extending section 24 c of the first rotor core base 24 is explainedas an example. As shown in FIG. 15A, the extending section 24 c isformed in a trapezoidal shape smaller in width toward the radial outerside when viewed from the axial direction and asymmetrical in thecircumferential direction. The extending section 24 c is formed in ashape in which the circumferential center P2 of the circumferentialdistal end portion is shifted to one side in the circumferentialdirection (the clockwise direction) with respect to the circumferentialcenter P1 at the radially proximal end portion. That is, a straight lineL1 passing the circumferential centers P1 and P2 of the proximal end andthe distal end of the extending section 24 c is formed not to beorthogonal to the axis of the rotating shaft 11.

The first rotor core 21 integrally includes the first rotor sideclaw-like magnetic poles 25 that project to one side in the axialdirection from the radially distal end portions (the outercircumferential side end portions) of the extending sections 24 c. Asshown in FIG. 15B, an outer circumferential surface 25 c (a surfaceopposed to the stator) of the first rotor side claw-like magnetic pole25 is formed in a symmetrical rectangular shape when viewed from theradial direction (the front). More specifically, a circumferentialcenter line L2 of the first rotor side claw-like magnetic pole 25 (astraight line passing the circumferential center X1 of the axiallyproximal end portion and the circumferential center X2 of the axiallydistal end portion) is parallel to the axial direction. The first rotorside claw-like magnetic pole 25 is formed in a shape line-symmetrical tothe circumferential center line L2 when viewed from the radialdirection.

The second rotor core 22 includes the extending sections 26 c and thesecond rotor side claw-like magnetic poles 27 respectively havingconfigurations same as the configurations of the extending sections 24 cand the first rotor side claw-like magnetic poles 25 of the first rotorcore 21.

Note that, when it is assumed that the rotor 12 shown in FIG. 14 rotatescounterclockwise, the extending sections 24 c and 26 c are formed inasymmetrical shapes in which the circumferential centers P2 of thedistal end portions are shifted in the counter rotating direction of therotor 12 with respect to the circumferential centers P1 of the proximalend portions.

With the configuration explained above, it is also possible to vary thereluctance torque according to the shapes of the extending sections 24 cand 26 c of the first and second rotor cores 21 and 22. As a result, itis possible to vary the motor performance (the torque and the output)even if the power supply to the stator 13 is the same.

The first and second stator cores 31 and 32 in the embodiment areconfigured such that the distal ends of the first and second stator sideclaw-like magnetic poles 35 and 37 are shifted in the circumferentialdirection. However, the first and second stator cores 31 and 32 are notlimited to this and may be configured such that the radially distal endsof the extending sections 34 b and 36 b are shifted in thecircumferential direction.

For example, as shown in FIGS. 16 and 17A and 17B, the extendingsections 34 b and 36 b of the first and second stator core bases 34 and36 are formed in shapes in which the radially distal end portions (theinner circumferential side end portions) thereof are shifted to one sidein the circumferential direction (in FIG. 16, the counterclockwisedirection).

The extending section 34 b of the first stator core base 34 is explainedas an example. As shown in FIG. 17A, the extending section 34 b isformed in a trapezoidal shape smaller in width toward the radial innerside when viewed from the axial direction and asymmetrical in thecircumferential direction. The extending section 34 b is formed in ashape in which a circumferential center P4 of the radially distal endportion is shifted to one side in the circumferential direction (thecounterclockwise direction) with respect to a circumferential center P3at the radially proximal end portion. That is, a straight line L3passing the circumferential centers P3 and P4 of the proximal end andthe distal end of the extending section 34 b is formed not to beorthogonal to the axis of the rotating shaft 11.

The first stator core 31 integrally includes the first stator sideclaw-like magnetic poles 35 projecting to one side in the axialdirection from the radially distal end portions (the innercircumferential side end portions) of the extending sections 34 b. Asshown in FIG. 17B, an inner circumferential surface 35 c (a surfaceopposed to the rotor) of the first stator side claw-like magnetic pole35 is formed in a symmetrical rectangular shape when viewed from theradial direction (the front). More specifically, a circumferentialcenter line L4 of the first stator side claw-like magnetic pole 35 (astraight line passing the circumferential center Z1 of the axiallyproximal end portion and the circumferential center Z2 of the axiallydistal end portion) is parallel to the axial direction. The first statorside claw-like magnetic pole 35 is formed in a shape line-symmetrical tothe circumferential center line L4 when viewed from the radialdirection.

The second stator core 32 includes the extending sections 36 b and thesecond stator side claw-like magnetic poles 37 respectively havingconfigurations same as the configurations of the extending sections 34 band the first stator side claw-like magnetic poles 35 of the firststator core 31.

Note that, when it is assumed that the rotor 12 rotatescounterclockwise, the extending sections 34 b and 36 b are formed inasymmetrical shapes in which the circumferential centers P4 of thedistal end portions are shifted in the rotating direction of the rotor12 with respect to the circumferential centers P3 of the proximal endportions.

With the configuration explained above, as in the configurationsexplained above, it is possible to vary the reluctance torque accordingto the shapes of the extending sections 34 b and 36 b of the first andsecond stator cores 31 and 32. As a result, it is possible to vary themotor performance (the torque and the output) even if the power supplyto the stator 13 is the same.

The shift direction (the shifting direction) of the radially distal endsides of the extending sections 24 c, 26 c, 34 b, and 36 b is notlimited to the examples shown in FIGS. 14 to 17B.

In FIGS. 18A and 18B, torques and outputs in various patterns in whichthe distal end shift directions of the extending sections 24 c, 26 c, 34b, and 36 b on the rotor 12 side and the stator 13 side are differentare respectively shown. In FIGS. 18A and 18B, a configuration in whichthe distal end shift direction is the counter rotating direction of therotor 12 is represented as pattern “L”, a configuration in which thedistal end shift direction is the rotating direction of the rotor 12 isrepresented as pattern “R”, and the conventional configuration (thesymmetrical shape) is represented as pattern “N”. In FIGS. 18A and 18B,the torque or the output of a configuration in which the patterns on themotor side and the stator side are “N/N” (the conventionalconfiguration) are set to 100%.

As shown in FIG. 18A, among combinations of the patterns, the torque isthe highest in a configuration in which the patterns of the rotor andthe stator side are “L/R” (the configuration shown in FIGS. 14 to 17B).The torque decreases in “L/N”, “L/L”, and “N/R” in order from thepattern. However, the torques in the patterns are higher than 100%. Thatis, by setting the extending sections 24 c, 26 c, 34 b, and 36 b of therotor and the stator side in these patterns, it is possible to improvethe torque.

The torque is equal to or lower than 100% in configurations in which thepatterns of the rotor and the stator side are “N/L”, “R/R”, “R/L”, and“R/N”. That is, by setting the extending sections 24 c, 26 c, 34 b, and36 b of the rotor and the stator side in these patterns, it is possibleto provide a motor that can obtain low torque.

In the combinations of the rotor 12 and the stator 13 shown in FIGS. 14and 16, when the rotor 12 rotates counterclockwise (regularly rotates),the patterns of the rotor and the stator side are “L/R”. However, whenthe rotor 12 rotates clockwise (reversely rotates), the patterns of therotor and the stator side are “R/L”. Consequently, when the rotor 12 isregularly and reversely rotated with the same power supply to the stator13, it is possible to reduce the torque in the reverse rotation withrespect to the torque in the regular rotation.

As shown in FIG. 18B, in configurations in which the patterns of therotor and the stator side are “L/R”, “L/N”, and “L/L”, the output ishigher than 100%. That is, by setting the extending sections 24 c, 26 c,34 b, and 36 b of the rotor and the stator side in these patterns, it ispossible to improve the output. Note that the output is the highest in aconfiguration in which the patterns of the rotor and the stator side are“L/R” (the configuration in the embodiment).

In configurations in which the patterns of the rotor and the stator sideare “N/R”, “N/L”, “R/R”, “R/L”, and “R/N”, the output is equal to orlower than 100%. That is, by setting the extending sections 24 c, 26 c,34B, and 36 b of the rotor and the stator side in these patterns, it ispossible to provide a motor that can obtain a low output.

As shown in FIGS. 18A and 18B, when the pattern of the rotor is “L”,that is, when the distal end shift directions of the extending sections24 c and 26 c of the first and second rotor cores 21 and 22 are thecounter rotating direction of the rotor 12, it is possible to improvethe torque and the output irrespective of the pattern of the stator.

Note that, in the example shown in FIGS. 14 to 17B, the distal end shiftdirections of the extending sections 24 c and 26 c of the first andsecond rotor cores 21 and 22 are the same direction. However, the distalend shift directions are not limited to this. The distal end shiftdirections may be opposite in the extending sections 24 c of the firstrotor core 21 and the extending sections 26 c of the second rotor core22. On the stator 13 side, similarly, the distal end shift direction ofthe extending sections 34 b of the first stator core 31 and the distalend shift direction of the extending section 36 b of the second statorcore 32 may be opposite to each other.

In the example shown in FIGS. 14 to 17B, distal end shift amounts (tiltsof the straight line L1 in the circumferential direction) of theextending sections 24 c and 26 c of the first and second rotor cores 21and 22 are set equal to each other. However, the distal end shiftamounts are not limited to this and may be set different in theextending sections 24 c on the first rotor core 21 side and theextending sections 26 c on the second rotor core 22 side. Similarly, inthe example shown in FIGS. 14 to 17B, distal end shift amounts (tilts ofthe straight line L3 in the circumferential direction) of the extendingsections 34 b and 36 b of the first and second stator cores 31 and 32are set equal to each other. However, the distal end shift amounts arenot limited to this and may be set different in the extending sections34 b on the first stator core 31 side and the extending sections 36 b onthe second stator core 32 side.

In the example shown in FIGS. 14 to 17B, the claw-like magnetic poles25, 27, 35, and 37 are formed in the rectangular shape in the radialdirection view (the symmetrical shape in the circumferential direction).However, the claw-like magnetic poles 25, 27, 35, and 37 are not limitedto this and may be formed in an asymmetrical shape as in the embodiment.

In the rotor 12 in the embodiment, the magnetization direction of themagnetic field magnet 23 in the V phase is a direction opposite to themagnetization direction of the magnetic field magnets 23 of the U phaseand the W phase. However, the magnetization directions are not limitedto this. The magnetization directions of the magnetic field magnets 23in the respective phases may be the same.

In the embodiment, the magnetic field magnet 23 is the ferrite magnet.However, besides the ferrite magnet, the magnetic field magnet 23 maybe, for example, a neodymium magnet.

In the embodiment, the rotor 12 (the stator 13) is configured by therotor sections 14 u, 14 v, and 14 w (the stator sections 30 u, 30 v, and30 w) of the three layers. However, the rotor sections 14 u, 14 v, and14 w (the stator sections 30 u, 30 v, and 30 w) may be configured by twoor less layers or for or more layers.

In the embodiment, the present invention is applied to the brushlessmotor 10 of the inner rotor type in which the rotor 12 is arranged onthe inner side of the stator 13. However, the present invention may beapplied to a motor of an outer rotor type.

Technical ideas that can be grasped from the first embodiment andanother example of the first embodiment are additionally explainedbelow.

(A) Inclined sections inclined with respect to the axial direction arerespectively formed at the circumferential end portions of the first andsecond claw-like magnetic poles of the rotor. In the inclined sectionsof the first claw-like magnetic poles and the inclined sections of thesecond claw-like magnetic poles, inclination angles thereof are set tobe different from each other.

(B) Inclined sections inclined with respect to the axial direction arerespectively formed at the circumferential end portions of the first andsecond claw-like magnetic poles of the stator. In the inclined sectionsof the first claw-like magnetic poles and the inclined sections of thesecond claw-like magnetic poles, inclination angles thereof are set tobe different from each other.

(C) The first and second claw-like magnetic poles of the rotor areconfigured such that the center positions thereof are arranged atunequal intervals in the circumferential direction.

(D) The first and second claw-like magnetic poles of the stator areconfigured such that the center positions thereof are arranged atunequal intervals in the circumferential direction.

With a motor described in (A) to (D) above, it is possible to vary themotor performance (the torque and the output) even if the power supplyto the stator is the same.

A motor according to a second embodiment (an example of a multi-Lundelltype motor) is explained below.

As shown in FIG. 19, a motor 110 in this embodiment includes a rotor 112including a rotating shaft 111 and an annular stator 113 firmly fixed toa motor housing (not shown in the figure) arranged on the outer side ofthe rotor 112.

The motor 110 is configured from single motor sections in three stagesstacked in the axial direction. The single motor sections in the threestages are configured in the order of a U-phase motor section Mu, aV-phase motor section Mv, and a W-phase motor section Mw from the top inFIG. 19.

As shown in FIGS. 20 and 26, the three motor sections Mu, Mv, and Mwrespectively include rotor sections (a U-phase rotor section Ru, aV-phase rotor section Rv, and a W-phase rotor section Rw) and statorsections (a U-phase stator section Su, a V-phase stator section Sv, anda W-phase stator section Sw). The rotor sections Ru, Rv, and Rw in therespective phases configure the rotor 112. The stator sections Su, Sv,and Sw in the respective phases configure the stator 113.

Configuration of the Rotor

As shown in FIG. 20, the rotor sections Ru, Rv and Rw in the threephases configuring the rotor 112 are stacked in order in the axialdirection. The rotor sections Ru, Rv, and Rw have substantially the sameconfigurations one another and are configured from first and secondrotor cores 121 and 122 and magnetic field magnets 123 sandwiched by thefirst and second rotor cores 121 and 122.

As shown in FIGS. 20 and 21, the first rotor core 121 includes adisk-like first rotor core base 124 including, in the radial center, athrough-hole 124 a through which the rotating shaft 111 is inserted andfixed. At the outer circumferential edge of the first rotor core base124, six first rotor side claw-like magnetic poles 125 are provided atequal intervals (60 degree intervals) one another.

The first rotor side claw-like magnetic pole 125 integrally includes aradially extending section 125 a extending from the outercircumferential edge of the first rotor core base 124 to the radialouter side and a first magnetic pole section 125 b projecting to oneside in the axial direction from the distal end portion (the radialouter side end portion) of the radially extending section 125 a. Notethat the first rotor side claw-like magnetic pole 125 may be formed bybending the first magnetic pole section 125 b at a right angle withrespect to the radially extending section 125 a. Alternatively, theradially extending section 125 a and the first magnetic pole section 125b may be integrally molded by casting.

The radially extending section 125 a is formed in a trapezoidal shapesmaller in width toward the radial outer side when viewed from the axialdirection. The first magnetic pole section 125 b is formed in atrapezoidal shape smaller in width toward the distal end when viewedfrom the radial direction. Both the circumferential side surfaces of thefirst rotor side claw-like magnetic poles 125 including the radiallyextending section 125 a and the first magnetic pole section 125 b areflat surfaces and are formed to be closer to each other toward theradial outer side. The first rotor side claw-like magnetic pole 125 isformed line-symmetrically to the circumferential center thereof.

As shown in FIG. 21, the second rotor core 122 is formed in a shape sameas the shape of the first rotor core 121 and includes a second rotorcore base 126 and second rotor side claw-like magnetic poles 127. Thesecond rotor core base 126 (a through-hole 126 a) and the second rotorside claw-like magnetic poles 127 (radially extending sections 127 a andsecond magnetic pole sections 127 b) are respectively formed in shapessame as the shapes of the first rotor core base 124 (the through-hole124 a) and the first rotor side claw-like magnetic poles 125 (theradially extending sections 125 a and the first magnetic pole sections125 b).

As shown in FIG. 20, the first rotor core 121 and the second rotor core122 are assembled such that the distal ends of the magnetic polesections 125 b and 127 b thereof face opposite directions each other.The second magnetic pole sections 127 b are arranged in thecircumferential direction between corresponding ones of the firstmagnetic pole sections 125 b. That is, the first magnetic pole sections125 b and the second magnetic pole sections 127 b are alternately linedin the circumferential direction in an assembled state.

Note that the axial length of the first magnetic pole section 125 b isset such that the distal end face of the first magnetic pole section 125b is in the same position as an opposed surface 126 b (the axially innerside surface) of the second rotor core base 126. Similarly, the axiallength of the second magnetic pole section 127 b is set such that thedistal end face of the second magnetic pole section 127 b is in the sameposition as an opposed surface 124 b (the axially inner side surface) ofthe first rotor core base 124.

In the assembled state of the first and second rotor cores 121 and 122,the first and second rotor core bases 124 and 126 are formed parallel toeach other. The magnetic field magnet 123 is arranged between the firstand second rotor core bases 124 and 126.

As shown in FIG. 21, the magnetic field magnet 123 is, for example, adisk-like permanent magnet formed by a ferrite magnet. A through-hole123 a, through which the rotating shaft 111 is inserted, is formed inthe center position of the magnetic field magnet 123. One end face 123 bof the magnetic field magnet 123 is in contact with the opposed surface124 b of the first rotor core base 124. The other end face 123 c of themagnetic field magnet 123 is in contact with the opposed surface 126 bof the second rotor core base 126. The magnetic field magnet 123 issandwiched and fixed in the axial direction between the first rotor corebase 124 and the second rotor core base 126. Note that the outerdiameter of the magnetic field magnet 123 is set to coincide with theouter diameter of the core bases 124 and 126.

The magnetic field magnet 123 is magnetized in the axial direction toset the first rotor core base 124 side as an N pole and set the secondrotor core base 126 side as an S pole. Therefore, the first rotor sideclaw-like magnetic poles 125 of the first rotor core 121 are caused tofunction as N poles (first magnetic poles) by the magnetic field magnet123. The second rotor side claw-like magnetic poles 127 of the secondrotor core 122 are caused to function as S poles (second magnetic poles)by the magnetic field magnet 123.

In the rotor sections Ru, Rv, and Rw formed in a so-called Lundell typestructure including the magnetic field magnets 123 as explained above,the first rotor side claw-like magnetic poles 125 functioning as the Npoles and the second rotor side claw-like magnetic poles 127 functioningas the S poles are alternately arranged in the circumferentialdirection. Each of the rotor sections Ru, Rv, and Rw is configured bytwelve poles (six pole pairs).

In this embodiment, an assembly form of the first and second rotor cores121 and 122 is different in the U-phase and W-phase rotor sections Ruand Rw in the upper and lower stages and the V-phase rotor section Rv inthe middle stage.

More specifically, as shown in FIGS. 20 and 23, the U-phase and W-phaserotor sections Ru and Rw in the upper and lower stages are formed in thesame shape each other. In the U-phase and W-phase rotor sections Ru andRw, the first and second rotor cores 121 and 122 are assembled such thatthe first magnetic pole sections 125 b of the first rotor side claw-likemagnetic pole 125 and the second magnetic pole sections 127 b of thesecond rotor side claw-like magnetic poles 127 are arranged at equalintervals (30 degree interval) in the circumferential direction.

On the other hand, as shown in FIGS. 20 and 23, in the V-phase rotorsection Rv in the middle stage, the first and second rotor cores 121 and122 are assembled such that the first magnetic pole sections 125 b andthe second magnetic pole sections 127 b are arranged at unequalintervals in the circumferential direction. That is, in the V-phaserotor section Rv, the first magnetic pole sections 125 b and the secondmagnetic pole sections 127 b are formed at equal intervals. However, thefirst magnetic pole section 125 b is assembled to be closer to one ofthe second magnetic pole sections 127 b on two sides thereof andseparated from the other. In this embodiment, the interval between thefirst and second magnetic pole sections 125 b and 127 b are set to 24degrees between the first and second magnetic pole sections 125 b and127 b close to each other and set to 36 degrees between the first andsecond magnetic pole sections 125 b and 127 b separated from each other.

A stacked structure of the rotor sections Ru, Rv, and Rw in therespective phases is explained.

As shown in FIG. 24, the U-phase rotor section Ru, the V-phase rotorsection Rv, and the W-phase rotor section Rw are stacked in order in theaxial direction to configure the rotor 112.

The V-phase rotor section Rv in the middle stage is stacked in areversed state with respect to the U-phase and W-phase rotor sections Ruand Rw in the upper and lower stages. That is, between the U phase andthe V phase, the second rotor core bases 126 are adjacent to each otherin the axial direction. Between the V phase and the W phase, the firstrotor core bases 124 are adjacent to each other in the axial direction.

Consequently, magnetization directions of the magnetic field magnets 123in the U phase and the W phase are set in the same direction (in FIG.24, upward). A magnetization direction of the magnetic field magnet 123in the V phase is set in a direction opposite to the magnetizationdirection of the magnetic field magnets 123 in the U phase and the Wphase. More specifically, S poles of the magnetic field magnets 123 inthe U phase and the V phase are opposed to each other via two secondrotor core bases 126 adjacent to each other. N poles of the magneticfield magnets 123 in the V phase and the W phase are opposed to eachother via two first rotor core bases 124 adjacent to each other. Thatis, magnetization directions of the rotor sections Ru, Rv, and Rw (themagnetic field magnets 123) are opposite to magnetization directions ofphases adjacent to each other.

Projecting directions in the axial direction of the first magnetic polesections 125 b (the first rotor side claw-like magnetic poles 125) ofthe U-phase and W-phase rotor sections Ru and Rw are the same direction(in FIG. 24, downward). On the other hand, a projecting direction of thefirst magnetic pole sections 125 b in the V phase is a direction (inFIG. 24, upward) opposite to the projecting direction of the firstmagnetic pole sections 125 b in the U phase and the W phase.

Similarly, projecting directions in the axial direction of the secondmagnetic pole sections 127 b (the second rotor side claw-like magneticpoles 127) of the U-phase and W-phase rotor sections Ru and Rw are thesame direction (in FIG. 24, upward). A projecting direction of thesecond magnetic pole sections 127 b in the V phase is a direction (inFIG. 24, downward) opposite to the projecting direction of the secondmagnetic pole sections 127 b in the U phase and the W phase.

The W-phase rotor section Rw is provided to be shifted 120 degrees inthe phase in the electrical angle (20 degrees in the mechanical angle)in the clockwise direction with respect to the U-phase rotor section Ruincluding the same configuration.

The V-phase rotor section Rv is provided such that the first rotor sideclaw-like magnetic pole 125 thereof (in FIG. 24, a first rotor sideclaw-like magnetic pole 125 v) is shifted 42 degrees in the electricalangle (7 degrees in the mechanical angle) in the clockwise directionwith respect to a first rotor side claw-like magnetic pole 125 u in theU phase. That is, a first rotor side claw-like magnetic pole 125 w inthe W phase is provided to be shifted 78 degrees in the electrical angle(13 degrees in the mechanical angle) in the clockwise direction withrespect to the first rotor side claw-like magnetic pole 125 v in the Vphase.

A second rotor side claw-like magnetic pole 127 v in the V phase isprovided to be shifted 78 degrees in the electrical angle (13 degrees inthe mechanical angle) in the clockwise direction with respect to asecond rotor side claw-like magnetic pole 127 u in the U phase. That is,a second rotor side claw-like magnetic pole 127 w in the W phase isprovided to be shifted 42 degrees in the electrical angle (7 degrees inthe mechanical angle) in the clockwise direction with respect to thesecond rotor side claw-like magnetic pole 127 v in the V phase.

As shown in FIG. 25, a configuration in which the first and second rotorside claw-like magnetic poles 125 v and 127 v in the V phase arearranged at equal intervals and shifted in the phase 60 degrees in theelectrical angle (10 degrees in the mechanical angle) in the clockwisedirection with respect to the U phase is set as a reference position.The first rotor side claw-like magnetic pole 125 v in the V phase inthis embodiment shown in FIG. 24 is shifted 18 degrees in the electricalangle (3 degrees in the mechanical angle) in the counterclockwisedirection with respect to the reference position. The second rotor sideclaw-like magnetic pole 127 v in the V phase in this embodiment shown inFIG. 24 is shifted 18 degrees in the electrical angle in the clockwisedirection with respect to the reference position.

That is, in the V-phase rotor section Rv in this embodiment, the firstrotor core 121 in the V phase (the first rotor side claw-like magneticpole 125 v) is shifted with respect to the reference position in arotating direction in which an overlapping width Lr1 in thecircumferential direction of the first rotor side claw-like magneticpoles 125 v and 125 w in the V phase and the W phase decreases.Similarly, the second rotor core 122 in the V phase (the second rotorside claw-like magnetic pole 127 v) is shifted with respect to thereference position in a rotating direction in which an overlapping widthLr2 in the circumferential direction of the second rotor side claw-likemagnetic poles 127 u and 127 v in the U phase and the V phase decreases.

Stator

As shown in FIG. 26, the stator 113 arranged on the radial outer side ofthe rotor 112 is configured from stator sections Su, Sv, and Sw in thethree phases (the U phase, the V phase, and the W phase) stacked in theaxial direction to correspond to the rotor sections Ru, Rv, and Rw. Thestator sections Su, Sv, and Sw have substantially the sameconfigurations one another and are configured from first and secondstator cores 131 and 132 and winding wires 133 arranged in the axialdirection between the first and second stator cores 131 and 132.

As shown in FIGS. 26 and 27, the first stator core 131 includes acylindrical first stator core base 134 centering on the axis of therotating shaft 111. On the inner circumferential surface of the firststator core base 134, six first stator side claw-like magnetic poles 135are provided at equal intervals (60 degree intervals) one another.

The first stator side claw-like magnetic pole 135 integrally includes aradially extending section 135 a extending from the innercircumferential surface of the first stator core base 134 to the radialinner side and a first magnetic pole section 135 b projecting to oneside in the axial direction from the distal end portion (the radialinner side end portion) of the radially extending section 135 a. Notethat the first stator side claw-like magnetic pole 135 may be formed bybending the first magnetic pole section 135 b at a right angle withrespect to the radially extending section 135 a. The radially extendingsection 135 a and the first magnetic pole section 135 b may beintegrally molded by casting.

The radially extending section 135 a is formed in a trapezoidal shapesmaller in width toward the radial inner side when viewed from the axialdirection. The first magnetic pole section 135 b is formed in atrapezoidal shape smaller in width toward the distal end when viewedfrom the radial direction. The first stator side claw-like magnetic pole135 is formed line-symmetrically with respect to a circumferentialcenter thereof.

As shown in FIG. 27, the second stator core 132 includes a configurationsame as the configuration of the first stator core 131 and includes asecond stator core base 136 and second stator side claw-like magneticpoles 137. The second stator core base 136 and the second stator sideclaw-like magnetic poles 137 (radially extending sections 137 a andsecond magnetic pole sections 137 b) are respectively formed in shapessame as the first stator core base 134 and the first stator sideclaw-like magnetic poles 135 (the radially extending section 135 a andthe first magnetic pole sections 135 b) of the shapes of the firststator core 131.

As shown in FIG. 26, the first and second stator core bases 134 and 136are set in contact with each other in the axial direction to configurethe outer circumferential walls of the stator sections Su, Sv, and Sw.In spaces on the inner circumferential sides of the first and secondstator core bases 134 and 136 and in the axial direction between theradially extending sections 135 a and 137 a, winding wires 133 formed ina ring shape in the circumferential direction of the rotating shaft 111are arranged.

The first stator core 131 and the second stator core 132 are assembledsuch that the distal ends of the magnetic pole sections 135 b and 137 bthereof face opposite directions each other. The second magnetic polesections 137 b are arranged in the circumferential direction betweencorresponding ones of the first magnetic pole sections 135 b. That is,the first magnetic pole sections 135 b and the second magnetic polesections 137 b are alternately lined in the circumferential direction inthe assembled state. The radially extending sections 135 a and 137 a ofthe first and second stator side claw-like magnetic poles 135 and 137are formed parallel to each other.

The stator sections Su, Sv, and Sw configured as explained above areformed in a so-called Lundell type (a claw pole type) structureincluding twelve poles that energize, with the winding wires 133, thefirst and second stator side claw-like magnetic poles 135 and 137 to bedifferent magnetic poles each other at every moment.

In the stator 113 in this embodiment, as in the case of the rotor 112,an assembly form of the first and second stator cores 131 and 132 isdifferent in the U-phase and W-phase stator sections Su and Sw in theupper and lower stages and the V-phase stator section Sv in the middlestage.

More specifically, as shown in FIGS. 26 and 28, the U-phase and W-phasestator sections Su and Sw in the upper and lower stages are formed inthe same shape each other. In the U-phase and W-phase stator sections Suand Sw, the first and second stator cores 131 and 132 are assembled suchthat the first magnetic pole sections 135 b of the first stator sideclaw-like magnetic pole 135 and the second magnetic pole sections 137 bof the second stator side claw-like magnetic poles 137 are arranged atequal intervals (30 degree interval) in the circumferential direction.

On the other hand, as shown in FIGS. 26 and 29, in the V-phase statorsection Sv in the middle stage, the first and second stator cores 131and 132 are assembled such that the first magnetic pole sections 135 band the second magnetic pole sections 137 b are arranged at unequalintervals in the circumferential direction. That is, in the V-phasestator section Sv, the first magnetic pole sections 135 b and the secondmagnetic pole sections 137 b are formed at equal intervals. However, thesecond magnetic pole section 135 b is assembled to be closer to one ofthe second magnetic pole sections 137 b on two sides thereof andseparated from the other. In this embodiment, the interval between thefirst and second magnetic pole sections 135 b and 137 b is set to 24degrees between the first and second magnetic pole sections 135 b and137 b close to each other and set to 36 degrees between the first andsecond magnetic pole sections 135 b and 137 b separated from each other.

A stacked structure of the stator sections Su, Sv, and Sw in therespective phases is explained.

As shown in FIG. 30, the U-phase stator section Su, the V-phase statorsection Sv, and the W-phase stator section Sw are stacked in order inthe axial direction to configure the stator 113. The stator sections Su,Sv, and Sw are stacked such that the first stator core base 134 and thesecond stator core base 136 are alternately arranged in the axialdirection.

The W-phase stator section Sw is provided to be shifted in the phase 120degrees in the electrical angle (20 degrees in the mechanical angle) inthe counterclockwise direction with respect to the U-phase statorsection Su including the same configuration.

The V-phase stator section Sv is provided such that the first statorside claw-like magnetic pole 135 thereof (in FIG. 30, a first statorside claw-like magnetic pole 135 v) is shifted 78 degrees in theelectrical angle (13 degrees in the mechanical angle) in thecounterclockwise direction with respect to a first stator side claw-likemagnetic pole 135 u in the U phase. That is, a first stator sideclaw-like magnetic pole 135 w in the W phase is provided to be shifted42 degrees in the electrical angle (7 degrees in the mechanical angle)in the counterclockwise direction with respect to the first stator sideclaw-like magnetic pole 135 v in the V phase.

A second stator side claw-like magnetic pole 137 v in the V phase isprovided to be shifted 42 degrees in the electrical angle (7 degrees inthe mechanical angle) in the counterclockwise direction with respect toa second stator side claw-like magnetic pole 137 u in the U phase. Thatis, a second stator side claw-like magnetic pole 137 w in the W phase isprovided to be shifted 78 degrees in the electrical angle (13 degrees inthe mechanical angle) in the counterclockwise direction with respect tothe second stator side claw-like magnetic pole 137 v in the V phase.

As shown in FIG. 31, a configuration in which the first and secondstator side claw-like magnetic poles 135 v and 137 v in the V phase arearranged at equal intervals and shifted in the phase 60 degrees in theelectrical angle (10 degrees in the mechanical angle) in thecounterclockwise direction with respect to the U phase is set as areference position. The first stator side claw-like magnetic pole 135 vin the V phase in this embodiment shown in FIG. 30 is shifted 18 degreesin the electrical angle (3 degrees in the mechanical angle) in thecounterclockwise direction with respect to the reference position. Thesecond stator side claw-like magnetic pole 137 v in the V phase in thisembodiment shown in FIG. 30 is shifted 18 degrees in the electricalangle in the clockwise direction with respect to the reference position.

That is, in the V-phase stator section Sv in this embodiment, the firststator core 131 (the first stator side claw-like magnetic pole 135 v) isshifted with respect to the reference position in a rotating directionin which an overlapping width Ls1 in the circumferential direction ofthe second stator side claw-like magnetic pole 137 u in the U phase andthe first stator side claw-like magnetic pole 135 v in the V phaseincreases. Similarly, the second stator core 132 in the V phase (thesecond stator side claw-like magnetic pole 137 v) is shifted withrespect to the reference position in a rotating direction in which anoverlapping width Ls2 in the circumferential direction of the secondstator side claw-like magnetic pole 137 v in the V phase and the firststator side claw-like magnetic pole 135 w in the W phase increases.

That is, as opposed to the rotor sections Ru, Rv, and Rw further shiftedin the clockwise direction in the U phase, the V phase, and the W phasetoward the axial direction, the stator sections Su, Sv, and Sw arefurther shifted in the counterclockwise direction in the U phase, the Vphase, and the W phase toward the axial direction. In other words, inthe rotor 112 and the stator 113, a sifting direction is reversed inunits of the sections in the respective phases.

Action of the motor 110 configured as explained above is explained.

When a three-phase alternating-current power supply voltage is appliedto the stator 113, a U-phase power supply voltage is applied to thewinding wire 133 of the U-phase stator section Su, a V-phase powersupply voltage is applied to the winding wire 133 of the V-phase statorsection Sv, and a W-phase power supply voltage is applied to the windingwire 133 of the W-phase stator section Sw. Consequently, a rotatingmagnetic field is generated in the stator 113 and the rotor 112 isdriven to rotate.

FIG. 32 is a graph of comparison of average torques of the configurationin this embodiment in which the claw-like magnetic poles 125, 127, 135,and 137 in the V phase are arranged at unequal intervals and a referenceconfiguration (see FIGS. 25 and 31) in which the claw-like magneticpoles 125, 127, 135, and 137 in the V phase are present in the referenceposition. As shown in FIG. 32, with the configuration in thisembodiment, average torque is improved to 110% or more with respect tothe reference configuration. This is considered to be because, on therotor 112 side, a magnetic flux is dispersed because the overlappingwidths Lr1 and Lr2 decrease with respect to the reference configurationand, as a result, torque is improved.

Characteristic advantages of the second embodiment are explained.

(3) The first and second stator side claw-like magnetic poles 135 and137 of the V-phase stator section Sv are arranged at unequal intervalsto increase the overlapping widths Ls1 in the circumferential directionbetween the first stator side claw-like magnetic poles 135 of theV-phase stator section Sv and the second stator side claw-like magneticpoles 137 of the U-phase stator sections Su with respect to thereference configuration, and to increase the overlapping widths Ls2 inthe circumferential direction between the second stator side claw-likemagnetic poles 137 of the V-phase stator section Sv and the first statorside claw-like magnetic poles 135 of the W-phase stator sections Sw withrespect to the reference configuration. The first and second rotor sideclaw-like magnetic poles 125 and 127 of the V-phase rotor section Rv arearranged at unequal intervals to reduce the overlapping widths Lr1 inthe circumferential direction between the first rotor side claw-likemagnetic poles 125 of the V-phase rotor section Rv and the first rotorside claw-like magnetic poles 125 of the W-phase rotor sections Rw withrespect to the reference configuration, and to reduce the overlappingwidths Lr2 in the circumferential direction between the second rotorside claw-like magnetic poles 127 of the V-phase rotor section Rv andthe second rotor side claw-like magnetic poles 127 of the U-phase rotorsections Ru with respect to the reference configuration. Consequently,it is possible to improve torque compared with the referenceconfiguration (see FIG. 32).

(4) The first and second rotor side claw-like magnetic poles 125 and 127of the rotor sections Ru, Rv, and Rw in the respective phases arerespectively provided at equal intervals in the circumferentialdirection. In the U-phase and W-phase rotor sections Ru and Rw, thefirst and second rotor cores 121 and 122 are assembled such that thefirst rotor side claw-like magnetic poles 125 and the second rotor sideclaw-like magnetic poles 127 are alternately arranged at equal intervalsin the circumferential direction. In the V-phase rotor section Rv, thefirst and second rotor cores 121 and 122 are assembled such that thefirst rotor side claw-like magnetic poles 125 and the second rotor sideclaw-like magnetic pole 127 are alternately arranged at unequalintervals in the circumferential direction. With this configuration, itis possible to arrange the first and second rotor side claw-likemagnetic poles 125 and 127 of the V-phase rotor section Rv at unequalintervals while forming the rotor cores 121 and 122 in the same shapeand attaining simplification of component management.

(5) The first and second stator side claw-like magnetic poles 135 and137 of the stator sections Su, Sv, and Sw in the respective phases arerespectively provided at equal intervals in the circumferentialdirection. In the U-phase and W-phase stator sections Su and Sw, thefirst and second stator cores 131 and 132 are assembled such that thefirst stator side claw-like magnetic poles 135 and the second statorside claw-like magnetic pole 137 are alternately arranged at equalintervals in the circumferential direction. In the V-phase statorsection Sv, the first and second stator cores 131 and 132 are assembledsuch that the first stator side claw-like magnetic poles 135 and thesecond stator side claw-like magnetic pole 137 are alternately arrangedat unequal intervals in the circumferential direction. With thisconfiguration, it is possible to arrange the first and second statorside claw-like magnetic poles 135 and 137 of the V-phase stator sectionSv at unequal intervals while forming the stator cores 131 and 132 inthe same shape and attaining simplification of component management.

Note that the second embodiment may be changed as explained below.

In the V-phase motor section My (the V-phase rotor section Rv and theV-phase stator section Sv), the arrangement of the claw-like magneticpoles 125, 127, 135, and 137 is not limited to the embodiment.

For example, as shown in FIG. 33, the first and second rotor cores 121and 122 in the V phase may be shifted with respect to the referenceconfiguration of the rotor 112 (see FIG. 25) in a rotating direction inwhich the overlapping widths Lr1 and Lr2 of the first and second rotorside claw-like magnetic poles 125 and 127 between the V and W phases andbetween the U and V phases increase. In an example shown in FIG. 33, thefirst rotor core 121 (the first rotor side claw-like magnetic pole 125v) in the V phase is shifted 18 degrees in the electrical angleclockwise and the second rotor core 122 (the second rotor side claw-likemagnetic pole 127 v) in the V phase is shifted 18 degrees in theelectrical angle counterclockwise with respect to the referenceconfiguration. With this configuration, as in the configurationexplained above, the first and second rotor side claw-like magneticpoles 125 v and 127 v in the V phase are arranged at unequal intervals.

As shown in FIG. 34, the first and second stator cores 131 and 132 inthe V phase may be shifted with respect to the reference configurationof the stator 113 (see FIG. 31) in a rotating direction in which theoverlapping widths Ls1 and Ls2 of the first and second stator sideclaw-like magnetic poles 135 and 137 between the U and V phases andbetween the V and W phases decrease. In an example shown in FIG. 34, thefirst stator core 131 (the first stator side claw-like magnetic pole 135v) in the V phase is shifted 18 degrees in the electrical angleclockwise and the second stator core 132 (the second stator sideclaw-like magnetic pole 137 v) in the V phase is shifted 18 degrees inthe electrical angle counterclockwise with respect to the referenceconfiguration. With this configuration, as in the configurationexplained above, the first and second stator side claw-like magneticpoles 135 v and 137 v in the V phase are arranged at unequal intervals.

In the V-phase motor section Mv, if the first and second stator sideclaw-like magnetic poles 135 v and 137 v are arranged at unequalintervals, the first rotor side claw-like magnetic poles 125 v and thesecond rotor side claw-like magnetic poles 127 v may be configured atequal intervals in the circumferential direction each other. Similarly,if the first and second rotor side claw-like magnetic poles 125 v and127 v are arranged at unequal intervals, the first stator side claw-likemagnetic poles 135 v and the second stator side claw-like magnetic poles137 v may be configured at equal intervals in the circumferentialdirection each other.

In FIG. 35, average torques in various patterns in which theconfigurations of the V-phase rotor section Rv and the V-phase statorsection Sv are different are shown.

In FIG. 35, of the rotor, the reference configuration (see FIG. 25) isrepresented as pattern “B”, a configuration in which the overlappingwidths Lr1 and Lr2 are reduced with respect to the pattern “B” (see FIG.24) is represented as pattern “A”, and a configuration in which theoverlapping widths Lr1 and Lr2 are increased with respect to the pattern“B” (see FIG. 33) is represented as pattern “C”.

Of the stator, the reference configuration (see FIG. 31) is representedas pattern “B”, a configuration in which the overlapping widths Ls1 andLs2 are increased with respect to the pattern “B” (see FIG. 30) isrepresented as pattern “A”, and a configuration in which the overlappingwidths Ls1 and Ls2 are reduced with respect to the pattern “B” (see FIG.34) is represented as pattern “C”.

In FIG. 35, average torque of the reference configuration in which thepatterns of the rotor and the stator side are “B/B” is set to 100%. Asshown in the figure, among combinations of the patterns, the torque isthe highest in a configuration in which the patterns of the rotor andthe stator side are “A/A” (the configuration in the embodiment). Thetorque decreases in “B/A”, “C/A”, and “A/B” in order from the pattern.However, the torques in the patterns are higher than 100%. That is, byadopting a combination of these patterns, it is possible to improve thetorque compared with the reference configuration.

The torque is equal to or lower than 100% in a configuration in whichthe patterns of the rotor and the stator side are “C/B”. The torquedecreases in “A/C”, “B/C”, and “C/C” in order from the pattern. That is,by adopting a combination of these patterns, it is possible to provide amotor that can obtain low torque.

By variously changing the arrangement in the circumferential directionof the claw-like magnetic poles 125, 127, 135, and 137 of the V-phasemotor section Mv, it is possible to vary the motor performance (thetorque) without changing power supply to the winding wires 133 and themagnetic field magnet 123. Consequently, with only a simpleconfiguration change of the V-phase motor section Mv, it is possible toobtain multi Lundell type motors of various specifications.

On the stator 113 side, if the pattern “A” in which the overlappingwidths Ls1 and Ls2 are increased with respect to the referenceconfiguration is adopted, it is possible to improve the torque from thetorque in the reference configuration irrespective of the pattern on therotor 112 side.

On the rotor 112 side, if the pattern “A” in which the overlappingwidths Lr1 and Lr2 are reduced with respect to the referenceconfiguration is adopted, it is possible to improve the torque from thetorques in the other patterns “B” and “C” under a condition in which thepattern on the stator 113 side is the same.

In the embodiment, the first and second rotor side claw-like magneticpoles 125 v and 127 v in the V phase are respectively formed at equalintervals in the circumferential direction in the first and second rotorcores 121 and 122. However, the first and second rotor side claw-likemagnetic poles 125 v and 127 v are not particularly limited to this andmay be formed at unequal intervals in the circumferential direction.

In the embodiment, the motor sections Mu, Mv, and Mw in the respectivephases are stacked without a gap. However, the motor sections Mu, Mv,and Mw are not particularly limited to this and may be arranged spacedapart from one another in the axial direction.

The number of the claw-like magnetic poles 125, 127, 135, and 137 (thenumber of magnetic poles) is not limited to the embodiment and may bechanged as appropriate according to a configuration.

In the embodiment, the magnetic field magnet 123 is the ferrite magnet.However, other than the ferrite magnet, the magnetic field magnet 123may be, for example, rare earth magnets such as a neodymium magnet, asamarium iron nitrogen magnet, and a samarium cobalt magnet.

In the embodiment, the present invention is applied to the motor 110 ofthe inner rotor type in which the rotor 112 is arranged on the innerside of the stator 113. However, the present invention may be applied toa motor of an outer rotor type.

A motor according to a third embodiment is explained.

FIG. 36 shows an overall perspective view of a brushless motor 210 inthis embodiment. An annular stator 212 firmly fixed to a motor housing(not shown in the figure) is arranged on the outer circumferential sideof a rotor 211 firmly fixed to a rotating shaft (not shown in thefigure).

The brushless motor 210 is configured from single motor sections in fourstages stacked in the axial direction. The single motor sections in thefour stages are configured in the order of a first U-phase motor sectionMu1, a V-phase motor section Mv, a W-phase motor section Mw, and asecond U-phase motor section Mu2 from the top in FIG. 36.

As shown in FIGS. 37 and 39, the motor sections Mu1, Mv, Mw, and Mu2 inthe four stages respectively include rotor sections (a first U-phaserotor section Ru1, a V-phase rotor section Rv, a W-phase rotor sectionRw, and a second U-phase rotor section Ru2) and stator sections (a firstU-phase stator section Su1, a V-phase stator section Sv, a W-phasestator section Sw, and a second U-phase stator section Su2). The rotorsections Ru1, Rv, Rw, and Ru2 configure the rotor 211. The statorsections Su1, Sv, Sw, and Su2 configure the stator 212.

Configuration of the Rotor

As shown in FIGS. 37 and 38, the rotor sections Ru1, Rv, Rw, and Ru2configuring the rotor 211 have the same configuration one another andare configured from first and second rotor cores 221 and 222 andmagnetic field magnets 223.

As shown in FIG. 38, the first rotor core 221 includes a first rotorcore base 224 formed in a ring plate shape. In the center position ofthe first rotor core base 224, a through-hole 221 a for inserting andfirmly fixing the rotating shaft (not shown in the figure) is formed. Onthe outer circumferential surface of the first rotor core base 224,twelve first rotor side claw-like magnetic poles 225 are projected tothe radial outer side at equal intervals in the circumferentialdirection. The distal ends of the first rotor side claw-like magneticpoles 225 are bent and formed to extend to the second rotor core 222side in the axial direction.

The first rotor side claw-like magnetic pole 225 is formed in atrapezoidal shape smaller in circumferential width toward the axiallydistal end side when viewed from the radial direction. That is, twocircumferential end faces 225 a and 225 b of the first rotor sideclaw-like magnetic pole 225 are flat surfaces and are formed to becloser to each other toward the axially distal end side. Note that thecircumferential width of the proximal end portions of the first rotorside claw-like magnetic poles 225 is set smaller than thecircumferential width of a gap between the first rotor side claw-likemagnetic poles 225 adjacent to each other.

The second rotor core 222 is formed of a material and in a shape same asthe material and the shape of the first rotor core 221. In the centerposition of the second rotor core base 226 formed in a substantiallydisk shape, a through-hole 222 a for inserting and firmly fixing therotating shaft (not shown in the figure) is formed. On the outercircumferential surface of the second rotor core base 226, twelve secondrotor side claw-like magnetic poles 227 are projected to the radialouter side at equal intervals. The distal ends of the second rotor sideclaw-like magnetic poles 227 are bent and formed to extend to the firstrotor core 221 side in the axial direction.

The second rotor side claw-like magnetic pole 227 is formed in atrapezoidal shape smaller in circumferential width toward the axiallydistal end side when viewed from the radial direction. That is, twocircumferential end faces 227 a and 227 b of the second rotor sideclaw-like magnetic pole 227 are flat surfaces and are formed to becloser to each other toward the axially distal end side. Note that thecircumferential width of the proximal end portions of the second rotorside claw-like magnetic poles 227 is set smaller than thecircumferential width of a gap between the second rotor side claw-likemagnetic poles 227 adjacent to each other.

The second rotor core 222 is arranged and fixed with respect to thefirst rotor core 221 such that the second rotor side claw-like magneticpoles 227 of the second rotor core 222 are respectively located betweencorresponding ones of the first rotor side claw-like magnetic poles 225of the first rotor core 221 when viewed from the axial direction. Inthis case, the second rotor core 222 is assembled to the first rotorcore 221 such that the magnetic field magnets 223 are arranged in theaxial direction between the first rotor core 221 and the second rotorcore 222.

More specifically, the magnetic field magnets 223 are sandwiched betweena surface (an opposed surface 224 a) on the second rotor core base 226side of the first rotor core base 224 and a surface (an opposed surface226 a) on the first rotor core base 224 side of the second rotor corebase 226.

In this case, one circumferential end face 225 a of the first rotor sideclaw-like magnetic pole 225 and the other circumferential end face 227 bof the second rotor side claw-like magnetic pole 227 are formed parallelto each other and formed in a substantially linear shape in which a gapbetween the circumferential end faces 225 a and 227 b is inclined in theaxial direction. The other circumferential end face 225 b of the firstrotor side claw-like magnetic pole 225 and one circumferential end face227 a of the second rotor side claw-like magnetic pole 227 are formedparallel to each other and formed in a substantially linear shape inwhich a gap between the circumferential end faces 225 b and 227 a areinclined with respect to the axial direction.

The magnetic field magnet 223 is, in this embodiment, a ring plate-likepermanent magnet made of a ferrite magnet. In the magnetic field magnet223, a through-hole 223 a, through which a rotating shaft (not shown inthe figure) is inserted, is formed in the center position thereof. Oneside surface 223 b of the magnetic field magnet 223 is in contact withthe opposed surface 224 a of the first rotor core base 224. The otherside surface 223 c of the magnetic field magnet 223 is in contact withthe opposed surface 226 a of the second rotor core base 226. Themagnetic field magnet 223 is sandwiched and fixed between the firstrotor core 221 and the second rotor core 222. Note that the outerdiameter of the magnetic field magnet 223 is set to coincide with theouter diameter of the first and second rotor core bases 224 and 226.

The magnetic field magnet 223 is magnetized in the axial direction toset the first rotor core 221 side as an N pole and set the second rotorcore 222 side as an S pole. Therefore, the first rotor side claw-likemagnetic poles 225 of the first rotor core 221 are caused to function asN poles (first magnetic poles) by the magnetic field magnet 223. Thesecond rotor side claw-like magnetic poles 227 of the second rotor core222 are caused to function as S poles (second magnetic poles) by themagnetic field magnet 223.

The rotor sections Ru1, Rv, Rw, and Ru2 configured in this way areformed in a so-called Lundell type structure including the magneticfield magnets 223. In the rotor sections Ru1, Rv, Rw, and Ru2, the firstrotor side claw-like magnetic poles 225 functioning as the N poles andthe second rotor side claw-like magnetic poles 227 functioning as the Spoles are alternately arranged in the circumferential direction. Each ofthe rotor sections Ru1, Rv, Rw, and Ru2 is configured by twenty-fourpoles (twelve pole pairs).

As shown in FIG. 37, the first U-phase rotor section Ru1, the V-phaserotor section Rv, the W-phase rotor section Rw, and the second U-phaserotor section Ru2 are stacked in order in the axial direction to formthe rotor 211.

When a configuration in which the first rotor core 221 is on the upperside and the second rotor core 222 is on the lower side with respect tothe magnetic field magnet 223 (a configuration in which a magnetizationdirection of the magnetic field magnet 223 is upward) is a frontwarddirection of the rotor sections Ru1, Rv, Rw, and Ru2, the first U-phaserotor section Ru1 and the W-phase rotor section Rw are stacked in thefrontward direction and the V-phase rotor section Rv and the secondU-phase rotor section Ru2 are stacked in a backward direction.Consequently, magnetization direction of the magnetic field magnets 223in the first U phase and the W phase are set in the same direction (inFIG. 37, upward) and a magnetization direction of the magnetic fieldmagnets 223 in the V phase and the second U phase is set in a directionopposite to the magnetization direction of the magnetic field magnets223 in the first U phase and the W phase.

The second rotor core bases 226 in the first U phase and the V phase areadjacent to each other in the axial direction. The S pole sides of themagnetic field magnets 223 in the first U phase and the V phase areopposed to each other via the adjacent second rotor core bases 226. Thefirst rotor core bases 224 in the V phase and the W phase are adjacentto each other in the axial direction. The N pole sides of the magneticfield magnets 223 in the V phase and the W phase are opposed to eachother via the adjacent first rotor core base 224. The second rotor corebases 226 in the W phase and the second U phase are adjacent to eachother in the axial direction. The S pole sides of the magnetic fieldmagnets 223 in the W phase and the second U phase are opposed to eachother via the adjacent second rotor core bases 226.

Extending directions in the axial direction of the first rotor sideclaw-like magnetic poles 225 in the first U phase and the W phase arethe same direction (in FIG. 37, the downward). An extending direction inthe axial direction of the first rotor side claw-like magnetic poles 225in the V phase and the second U phase is a direction opposite to thedirection. Note that the axially distal ends of the first rotor sideclaw-like magnetic poles 225 in the first U phase and the first rotorside claw-like magnetic poles 225 in the V phase are separated from eachother in the axial direction. The axially distal ends of the first rotorside claw-like magnetic poles 225 in the W phase and the first rotorside claw-like magnetic poles 225 in the second U phase are alsoseparated from each other in the axial direction.

Similarly, extending directions in the axial direction of the secondrotor side claw-like magnetic poles 227 in the first U phase and the Wphase are the same direction (in FIG. 37, upward). An extendingdirection in the axial direction of the second rotor side claw-likemagnetic poles 227 in the V phase and the second U phase is a directionopposite to the direction. Note that the axially distal ends of thesecond rotor side claw-like magnetic poles 227 in the V phase and thesecond rotor side claw-like magnetic poles 227 in the W phase areseparated from each other in the axial direction.

The first U-phase rotor section Ru1, the V-phase rotor section Rv, theW-phase rotor section Rw, and the second U-phase rotor section Ru2 arestacked with the phases shifted 60 degrees in the electrical angle (5degrees in the mechanical angle) from one another. More specifically,the V-phase rotor section Rv is firmly fixed to the rotating shaft withthe phase shifted 60 degrees in the electrical angle in thecounterclockwise direction with respect to the first U-phase rotorsection Ru1. The W-phase rotor section Rw is firmly fixed to therotating shaft with the phase shifted 60 degrees in the electrical anglein the counterclockwise direction with respect to the V-phase rotorsection Rv. The second U-phase rotor section Ru2 is firmly fixed to therotating shaft with the phase shifted 60 degrees in the electrical anglein the counterclockwise direction with respect to the W-phase rotorsection Rw.

Configuration of the Stator

As shown in FIGS. 39 and 40, the stator sections Su1, Sv, Sw, and Su2configuring the stator 212 are stacked in the axial direction to berespectively opposed to the first U-phase rotor section Ru1, the V-phaserotor section Rv, the W-phase rotor section Rw, and the second U-phaserotor section Ru2 corresponding thereto in the radial direction. Thestator sections Su1, Sv, Sw, and Su2 have the same configuration oneanother and are configured from first and second stator cores 231 and232 and a coil section 233.

The first stator core 231 includes a cylindrical first stator core base234 and first stator side claw-like magnetic poles 235 extending to theradial inner side from the first stator core base 234 and bent to thesecond stator core 232 side in the axial direction at the inner sidedistal end portion thereof. Twelve first stator side claw-like magneticpoles 235 are formed at equal intervals in the circumferentialdirection.

The first stator side claw-like magnetic pole 235 is formed in atrapezoidal shape smaller in circumferential width toward the axiallydistal end side when viewed from the radial direction. That is, twocircumferential end faces 235 a and 235 b of the first stator sideclaw-like magnetic poles 235 are flat surfaces and are formed to becloser to each other toward the axially distal end side. Note that thecircumferential width of the proximal end portions of the first statorside claw-like magnetic poles 235 is set larger than the circumferentialwidth of a gap between the first stator side claw-like magnetic poles235 adjacent to each other.

As shown in FIG. 40, the second stator core 232 is formed of a materialand in a shape same as the material and the shape of the first statorcore 231. The second stator core 232 includes a cylindrical secondstator core base 236 and second stator side claw-like magnetic poles 237extending to the radial inner side from the second stator core base 236and bent to the first stator core 231 side in the axial direction at theinner side distal end portion thereof. Twelve second stator sideclaw-like magnetic poles 237 are formed at equal intervals in thecircumferential direction. Annular distal end faces of the first andsecond stator core bases 234 and 236 are set in contact with each otherin the axial direction.

The second stator side claw-like magnetic pole 237 is formed in atrapezoidal shape smaller in circumferential width toward the axiallydistal end side when viewed from the radial direction. That is, twocircumferential end faces 237 a and 237 b of the second stator sideclaw-like magnetic pole 237 are flat surfaces and are formed to becloser to each other toward the axially distal end side. Note that thecircumferential width of the proximal end portions of the second statorside claw-like magnetic poles 237 is set larger than the circumferentialwidth of a gap between the second stator side claw-like magnetic poles237 adjacent to each other.

The second stator core 232 is arranged and fixed with respect to thefirst stator core 231 such that the second stator side claw-likemagnetic poles 237 of the second stator core 232 are respectivelylocated between corresponding ones of the first stator side claw-likemagnetic poles 235 of the first stator core 231 when viewed from theaxial direction. Note that the second stator core 232 is assembled tothe first stator core 231 such that the coil section 233 is arranged inthe axial direction between the first stator core 231 and the secondstator core 232.

In an assembled state, one circumferential end face 235 a of the firststator side claw-like magnetic pole 235 and the other circumferentialend face 237 b of the second stator side claw-like magnetic pole 237 areformed in parallel to each other and formed in a substantially linearshape in which a gap between the circumferential end faces 235 a and 237b is inclined with respect to the axial direction. The othercircumferential end face 235 b of the first stator side claw-likemagnetic pole 235 and one circumferential end face 237 a of the secondstator side claw-like magnetic pole 237 are formed in parallel to eachother and formed in a substantially linear shape in which a gap betweenthe circumferential end faces 235 b and 237 a is inclined with respectto the axial direction.

Note that the length in the axial direction from the axial outer sidesurface (a surface on a counter coil section side) of the first statorcore 231 to the axial outer side surface of the second stator core 232is set the same as the length in the axial direction from the axialouter side surface (the rear surface of the opposed surface 224 a) ofthe first rotor core base 224 to the axial outer side surface (the rearsurface of the opposed surface 226 a) of the second rotor core base 226.

The coil section 233 is formed in an annular shape centering on the axisof the rotating shaft and is configured by internally providing awinding wire in a bobbin. The coil section 233 is arranged between thefirst and second stator core bases 234 and 236 and the first and secondstator side claw-like magnetic poles 235 and 237 in the radialdirection. Note that, in FIG. 40, for convenience of explanation, adraw-out terminal of the coil section 233 is not shown in the figure.

The stator sections Su1, Sv, Sw, and Su2 configured as explained aboveform a stator of a so-called Lundell type (a claw pole type) structureincluding twenty-four poles that energize, with the coil section 233between the first and second stator cores 231 and 232, the first andsecond stator side claw-like magnetic poles 235 and 237 to be differentmagnetic poles each other at every moment.

As shown in FIG. 39, the first U-phase stator section Su1, the V-phasestator section Sv, the W-phase stator section Sw, and the second U-phasestator section Su2 are stacked in order in the axial direction to formthe stator 212. The stator sections Su1, Sv, Sw, and Su2 are stacked inthe axial direction such that the first stator core base 234 and thesecond stator core base 236 are alternately arranged in the axialdirection. The distal ends of the first stator side claw-like magneticpoles 235 in the respective phases face one side in the axial direction(in FIG. 39, downward). The distal ends of the second stator sideclaw-like magnetic poles 237 in the respective phase face the other sidein the axial direction (in FIG. 39, upward).

The first U-phase stator section Su1, the V-phase stator section Sv, theW-phase stator section Sw, and the second U-phase stator section Su2 arestacked with the phases shifted 60 degrees in the electrical angle (5degrees in the mechanical angle) from one another. More specifically,the V-phase stator section Sv is provided with the phase shifted 60degrees in the electrical angle in the clockwise direction with respectto the first U-phase stator section Su1. The W-phase stator section Swis provided with the phase shifted 60 degrees in the electrical angle inthe clockwise direction with respect to the V-phase stator section Sv.The second U-phase stator section Su2 is provided with the phase shifted60 degrees in the electrical angle in the clockwise direction withrespect to the W-phase stator section Sw.

That is, a direction of inclination with respect to the axial directionformed by the shift of the four rotor sections Ru1, Rv, Rw, and Ru2 whenviewed from the radial direction and a direction of inclination withrespect to the axial direction formed by the shift of the four statorsections Su1, Sv, Sw, and Su2 when viewed from the radial direction areopposite directions each other on opposed surfaces of the rotor 211 andthe stator 212. Consequently, it is possible to cause the first andsecond rotor side claw-like magnetic poles 225 and 227 in the respectivephases to suitably follow switching of the magnetic poles of the firstand second stator side claw-like magnetic poles 235 and 237. As aresult, it is possible to realize suitable rotation of the rotor 211.

A U-phase power supply voltage of a three-phase alternating-currentpower supply is applied to the coil sections 233 of the first and secondU-phase stator sections Su1 and Su2, a V-phase power supply voltage ofthe three-phase alternating-current power supply is applied to the coilsection 233 of the V-phase stator section Sv, and a W-phase power supplyvoltage of the three-phase alternating-current power supply is appliedto the coil section 233 of the W-phase stator section Sw.

The stator sections Su1, Sv, Sw, and Su2 explained above arerespectively arranged on the outer circumferential sides of the rotorsections Ru1, Rv, Rw, and Ru2 corresponding thereto to configure themotor sections Mu1, Mv, Mw, and Mu2. Note that all the axial thicknessesof the rotor sections Ru1, Rv, Rw, and Ru2 and the stator sections Su1,Sv, Sw, and Su2 are set equal.

Action of the brushless motor 210 configured as explained above isexplained.

When a three-phase alternating-current power supply voltage is appliedto the stator 212, a U-phase power supply voltage is applied to the coilsections 233 of the first and second U-phase stator sections Su1 andSu2, a V-phase power supply voltage is applied to the coil section 233of the V-phase stator section Sv, and a W-phase power supply voltage isapplied to the coil section 233 of the W-phase stator section Sw.Consequently, a rotating magnetic field is generated in the stator 212and the rotor 211 is driven to rotate. In this case, the V-phase powersupply voltage and the W-phase power supply voltage respectivelysupplied to the V-phase and W-phase stator sections Sv and Sw are setequal to each other. The U-phase power supply voltage supplied to thefirst and second U-phase stator sections Su1 and Su2 is set to a halfvalue of the V-phase power supply voltage and the W-phase power supplyvoltage. That is, a total of the U-phase power supply voltages suppliedto the first and second U-phase stator sections Su1 and Su2 is equal tothe V-phase power supply voltage and the W-phase power supply voltage.

The brushless motor 210 in this embodiment is configured in a four-stagestructure in which the first U-phase motor section Mu1, the V-phasemotor section Mv, the W-phase motor section Mw, and the second U-phasemotor section Mu2 are stacked in order in the axial direction. That is,the first U-phase motor section Mu1 and the second U-phase motor sectionMu2 are respectively arranged in stages at two ends of the four stages.

FIG. 41A is a graph of induced voltages in the respective phases in theconventional motor of the three-stage structure in which the U phase,the V phase, and the W phase are arranged in order stage by stage tocorrespond to the three-phase alternating-current power supply. FIG. 41Bis a graph of induced voltages in the respective phases in the brushlessmotor 210 in this embodiment.

As shown in FIG. 41A, in the conventional motor, an induced voltage inthe V phase located in the middle stage among the induced voltagesgenerated in the respective phases is the highest. The magnitude ofinduced voltages in the U phase and the V phase is 95% with respect tothe magnitude of the induced voltage in the V phase. That is, adifference of induced voltages in the other two phases from the inducedvoltage in the V phase, which is largest among the phases is 5%.

On the other hand, as shown in FIG. 41B, in the brushless motor 210 inthis embodiment, an induced voltage in the U phase, which is a total ofinduced voltages generated in the first and second U-phase motorsections Mu1 and Mu2 located in the stages at two ends, is the highestamong the induced voltages generated in the respective phases. Inducedvoltages in the V phase and the W phase located in the middle stage areequal to each other. The magnitude of the induced voltages in the Vphase and the W phase is 98% of the magnitude of the induced voltage inthe U phase. That is, a difference of induced voltages in the other twophases from the induced voltage in the U phase, which is the largestamong other phases is 2%. Compared with the conventional motor, abalance of the induced voltages generated in the respective phases isimproved.

In the conventional motor, a magnetic flux easily leaks in single motorsections in the U phase and the W phase located at two ends. Therefore,the magnitudes of induced voltages generated in the single motorsections in the U phase and the W phase and a single motor section inthe V phase are different. Therefore, in the structure in thisembodiment, a single motor section in the U phase is added such that thesingle motor section in the W phase is not a stage at an end. With thestructure in this embodiment, it is possible to improve a balance of theinduced voltages generated in the respective phases.

The motor sections Mu1, Mv, Mw, and Mu2 are arranged in the order of theU phase, the V phase, the W phase, and the U phase. Therefore, atransition of magnetic flux generation among the phases is smoothlyperformed. As a result, it is possible to contribute to improvement ofmotor performance.

In this embodiment, the rotor sections Ru1, Rv, Rw, and Ru2 are formedin the Lundell structure. Therefore, when a change in the number ofmagnetic poles is requested, the number of poles can be easily changedby changing the number of the first and second rotor side claw-likemagnetic poles 225 and 227 while forming the magnetic field magnets 223in the same structure. Similarly, the stator sections Su1, Sv, Sw, andSu2 are formed in the Lundell type (the claw pole type) structure.Therefore, the number of poles is easily changed by changing the numberof the first and second stator side claw-like magnetic poles 235 and 237while forming the coil sections 233 in the same structure. That is, inthe brushless motor 210 in this embodiment, it is possible to easilycope with, without involving a large design change, a specificationchange in which the numbers of magnetic poles of the rotor 211 and thestator 212 are variously combined.

In this embodiment, in the magnetic field magnets 223 of the firstU-phase and W-phase rotor sections Ru1 and Rv, magnetization directionsare set opposite to the magnetization directions of the magnetic fieldmagnets 223 of the V-phase and second U-phase rotor sections Rv and Ru2.Consequently, the same polarities of the magnetic field magnets 223 instages adjacent to each other are opposed to each other. Therefore,magnetic fluxes of the magnetic field magnets 223 less easily leak tothe motor sections Mu1, Mv, Mw, and Mu2 sides adjacent to one another.As a result, an effective magnetic flux contributing to the rotation ofthe rotor 211 is efficiently improved.

Characteristic advantages of the third embodiment are explained.

(6) The single motor sections arranged in a plurality of stages includethe two U-phase motor sections Mu1 and Mu2, the one V-phase motorsection Mv, and the one W-phase motor section Mw. The U-phase motorsections Mu1 and Mu2 are arranged in the stages at the axial two ends.With this configuration, it is possible to improve a balance of inducedvoltages generated in the respective phases (see FIGS. 41A and 41B). Asa result, it is possible to suppress the motor performance from beingdeteriorated by imbalance of the induced voltages in the respectivephases. Further, by forming the motor sections Mu1, Mv, Mw, and Mu2 inthe four stage configuration, it is possible to improve the balance ofthe induced voltages generated in the respective phases whilesuppressing an increase in size in the axial direction as much aspossible.

(7) On the axial two sides of the V-phase motor section Mv, the firstU-phase motor section Mu1 and the W-phase motor section Mw arerespectively arranged. On the axial two sides of the W-phase motorsection Mw, the V-phase motor section Mv and the second U-phase motorsection Mu2 are respectively arranged. With this configuration, twosingle motor sections of the other phase are respectively arranged ontwo sides of the V-phase and W-phase motor sections Mv and Mw (i.e., themotor sections are arranged in the order of the U phase, the V phase,the W phase, and the U phase). Therefore, a transition of magnetic fluxgeneration among the phases is smoothly performed. It is possible tocontribute to the improvement of the motor performance.

Note that the third embodiment may be changed as explained below.

In the embodiment, the brushless motor 210 is configured in the fourstage structure by the four single motor sections (the first U-phasemotor section Mu1, the V-phase motor section Mv, the W-phase motorsection Mw, and the second U-phase motor section Mu2). However, themotor sections are not limited to this. The number of stages may bechanged as appropriate as long as the numbers of the V-phase and W-phasemotor sections Mv and Mw are the same number (n) and the number ofU-phase motor sections is (n+1).

For example, the brushless motor 210 may have a configuration includinga seven stage structure including three U-phase motor sections and twoV-phase motor sections and two W-phase motor sections, two among thethree U-phase motor sections being arranged in stages at two ends. Withthis configuration, it is possible to obtain effects substantially thesame as the effects in the embodiment. In this case, it is preferable toarrange the single motor sections in the seven stages in the order ofthe U phase, the V phase, the W phase, the U phase, the V phase, the Wphase, and the U phase. Consequently, a transition of magnetic fluxgeneration among the phases is smoothly performed. It is possible tocontribute to improvement of the motor performance.

In this embodiment, the motor sections Mu1, Mv, Mw, and Mu2 are stackedwithout a gap. However, the motor sections Mu1, Mv, Mw, and Mu2 are notlimited to this. The motor sections Mu1, Mv, Mw, and Mu2 may be arrangedspaced from one another in the axial direction.

The number of the claw-like magnetic poles 225, 227, 235, and 237 (thenumber of magnetic poles) is not limited to the embodiment and may bechanged as appropriate according to a configuration.

In the rotor 211 in the embodiment, all magnetization directions of themagnetic field magnets 223 in the respective phases may be set in thesame direction.

In the embodiment, the magnetic field magnet 223 is the ferrite magnet.However, other than the ferrite magnet, the magnetic field magnet 223may be, for example, a neodymium magnet.

In the embodiment, the present invention is applied to the brushlessmotor 210 of the inner rotor type in which the rotor 211 is arranged onthe inner side of the stator 212. However, the present invention may beapplied to a motor of an outer rotor type.

A motor according to a fourth embodiment is explained below withreference to FIGS. 42 to 53.

As shown in FIGS. 42 and 43, a brushless motor 301 includes a rotor 302firmly fixed to a rotating shaft (not shown in the figure) and anannular stator 303 arranged on the outer side of the rotor 302 andfirmly fixed to a not-shown motor housing. Note that the not-shownrotating shaft is rotatably supported by a bearing attached to thenot-shown motor housing.

Rotor 302

As shown in FIGS. 45 and 46, the rotor 302 includes first and secondrotor cores 311 and 321, magnetic field magnets 331, and first andsecond annular auxiliary magnets 341 and 351.

First Rotor Core 311

As shown in FIGS. 44 and 46, the first rotor core 311 includes a firstrotor core base 314 formed by an electromagnetic steel plate formed in adisk shape. In the center position of the first rotor core base 314, athrough-hole 311 a for inserting and firmly fixing the rotating shaft(not shown in the figure) is formed.

On an outer circumferential surface 314 c of the first rotor core base314, twelve first rotor side claw-like magnetic poles 315 formed in thesame shape are projected to the radial outer side at equal intervals.The distal ends of the first rotor side claw-like magnetic poles 315 arebent and formed to extend to the second rotor core 321 side in the axialdirection.

As shown in FIG. 44, in the first rotor side claw-like magnetic pole315, a portion projecting to the radial outer side from the outercircumferential surface 314 c of the first rotor core base 314 is formedlarger in thickness (length in the axial direction) than the thickness(the length in the axial direction) of the first rotor core base 314 andis formed as a first step section 315 d. The first step section 315 d isformed to be thicker to the second rotor core 321 side. A horizontalsurface (hereinafter referred to as first back surface 315 m) on acounter second rotor core 321 side is flush with a counter opposedsurface 314 b of the first rotor core base 314.

A first step surface 315 e formed on the radial inner side of the firststep section 315 d is, when viewed from the axial direction, an arcuatesurface concentric with the outer circumferential surface 314 c of thefirst rotor core base 314 centering on a center axis O of the not-shownrotating shaft.

A first magnetic pole section 315 f is formed to extend to the secondrotor core 321 side in the axial direction from the radial outer sideend of the first step section 315 d, whereby the first rotor sideclaw-like magnetic pole 315 is formed. Two circumferential end faces 315a and 315 b of the first rotor side claw-like magnetic pole 315including the first step section 315 d and the first magnetic polesection 315 f are flat surfaces and are formed to be closer to eachother toward the distal ends.

That is, a shape of the first step section 315 d when viewed from theaxial direction is a trapezoidal shape smaller in width toward theradial outer side. A shape of the first magnetic pole section 315 f whenviewed from the radial direction is a trapezoidal shape smaller in widthtoward the distal end.

The first magnetic pole section 315 f of the first rotor side claw-likemagnetic pole 315 is formed in a fan shape in a cross section in adirection orthogonal to the axis direction. An outer side surface 315 jand an inner side surface 315 k in the radial direction of the firstmagnetic pole section 315 f are, when viewed from the axial direction,arcuate surfaces concentric with the outer circumferential surface 314 cof the first rotor core base 314 centering on the center axis O.

An angle in the circumferential direction of the first rotor sideclaw-like magnetic poles 315, that is, an angle formed by thecircumferential end faces 315 a and 315 b with respect to the centeraxis O of the rotating shaft (not shown in the figure) is set smallerthan an angle of a gap between the first rotor side claw-like magneticpoles 315 adjacent to each other.

Second Rotor Core 321

As shown in FIG. 46, the second rotor core 321 is formed of a materialand in a shape same as the material and the shape of the first rotorcore 311. In the center position of the second rotor core base 324formed by an electromagnetic steel plate formed in a disk shape, athrough-hole 321 a for inserting and firmly fixing the rotating shaft(not shown in the figure) is formed.

On the outer circumferential surface of the second rotor core base 324,twelve second rotor side claw-like magnetic poles 325 formed in the sameshape are projected to the radial outer side at equal intervals. Thedistal ends of the second rotor side claw-like magnetic poles 325 arebent and formed to extend to the first rotor core 311 side in the axialdirection.

As shown in FIG. 44, in the second rotor side claw-like magnetic pole325, a portion projecting to the radial outer side from an outercircumferential surface 324 c of the second rotor core base 324 isformed larger in thickness (length in the axial direction) than thethickness (the length in the axial direction) of the second rotor corebase 324 and is formed as a second step section 325 d. The second stepsection 325 d is formed to be thicker to the first rotor core 311 side.A horizontal surface (hereinafter referred to as second back surface 325m) on a counter first rotor core 311 side is flush with a counteropposed surface 324 b of the second rotor core base 324.

A second step surface 325 e formed on the radial inner side of thesecond step section 325 d is, when viewed from the axial direction, anarcuate surface concentric with the outer circumferential surface 324 cof the second rotor core base 324 centering on the center axis O.

A second magnetic pole section 325 f is formed to extend to the firstrotor core 311 side in the axial direction from the radial outer sideend of the second step section 325 d, whereby the second rotor sideclaw-like magnetic pole 325 is formed. Two circumferential end faces 325a and 325 b of the second rotor side claw-like magnetic pole 325including the second step section 325 d and the second magnetic polesection 325 f are flat surfaces and are formed to be closer to eachother toward the distal ends.

That is, a shape of the second step section 325 d when viewed from theaxial direction is a trapezoidal shape smaller in width toward theradial outer side. A shape of the second magnetic pole section 325 fwhen viewed from the radial direction is a trapezoidal shape smaller inwidth toward the distal end.

The second magnetic pole section 325 f of the second rotor sideclaw-like magnetic pole 325 is formed in a fan shape in a cross-sectionin the direction orthogonal to the axis direction. An outer side surface325 j and an inner side surface 325 k in the radial direction of thesecond magnetic pole section 325 f are, when viewed from the axialdirection, arcuate surfaces concentric with the outer circumferentialsurface 314 c of the first rotor core base 314 centering on the centeraxis O.

An angle in the circumferential direction of the second rotor sideclaw-like magnetic poles 325, that is, an angle formed by thecircumferential end faces 325 a and 325 b with respect to the centeraxis O of the rotating shaft (not shown in the figure) is set smallerthan an angle of a gap between the second rotor side claw-like magneticpoles 325 adjacent to each other.

The second rotor core 321 is arranged and fixed with respect to thefirst rotor core 311 such that the second rotor side claw-like magneticpoles 325 of the second rotor core 321 are respectively located amongthe first rotor side claw-like magnetic poles 315 of the first rotorcore 311 when viewed from the axial direction. In this case, the secondrotor core 321 is assembled to the first rotor core 311 such that themagnetic field magnets 331 are arranged in the axial direction betweenthe first rotor core 311 and the second rotor core 321.

Magnetic Field Magnet 331

As shown in FIG. 46, in this embodiment, the magnetic field magnet 331is a disk-like permanent magnet formed by a ferrite magnet. Athrough-hole 332, through which the rotating shaft (not shown in thefigure) is inserted, is formed in the center position of the magneticfield magnet 331. One side surface 333 of the magnetic field magnet 331is in contact with an opposed surface 314 a of the first rotor core base314. The other side surface 334 of the magnetic field magnet 331 is incontact with an opposed surface 324 a of the second rotor core base 324.The magnetic field magnet 331 is sandwiched and fixed between the firstrotor core 311 and the second rotor core 321.

The outer diameter of the magnetic field magnet 331 is set to coincidewith the outer diameter of the first and second rotor core bases 314 and324 (the outer circumferential surfaces 314 c and 324 c).

Therefore, when the magnetic field magnet 331 is sandwiched by the firstrotor core base 314 and the second rotor core base 324, as shown in FIG.44, the first and second step sections 315 d and 325 d and the first andsecond step surfaces 315 e and 325 e of the first and second rotor sideclaw-like magnetic poles 315 and 325 are in contact with an outercircumferential surface 335 of the magnetic field magnet 331.

The thickness (the length in the axial direction) of the magnetic fieldmagnet 331 is set to thickness decided in advance. In this embodiment,as shown in FIG. 44, the first and second rotor side claw-like magneticpoles 315 and 325 are set to length at which distal end faces 315 c and325 c thereof are respectively flush with the opposed surfaces 314 a and324 a of the first and second rotor core bases 314 and 324.

As shown in FIG. 44, the magnetic field magnet 331 is magnetized in theaxial direction to set the first rotor core 311 side as an N pole andset the second rotor core 321 side as an S pole. Therefore, the firstrotor side claw-like magnetic poles 315 of the first rotor core 311 arecaused to function as N poles (first magnetic poles) by the magneticfield magnet 331. The second rotor side claw-like magnetic poles 325 ofthe second rotor core 321 are caused to function as S poles (secondmagnetic poles) by the magnetic field magnet 331.

The rotor 302 configured as explained above is a rotor of a so-calledLundell type structure including the magnetic field magnets 331. Therotor 302 is a rotor including twenty-four magnetic poles (twelve polepairs) in which the first rotor side claw-like magnetic poles 315functioning as the N poles and the second rotor side claw-like magneticpoles 325 functioning as the S poles are alternately arranged in thecircumferential direction.

First Annular Auxiliary Magnet 341

As shown in FIGS. 45 and 46, the first annular auxiliary magnet 341 isfirmly fixed on the counter second rotor core 321 side of the firstrotor core 311.

More specifically, as shown in FIGS. 44 and 46, the first rotor sideclaw-like magnetic poles 315 of the first rotor core 311 respectivelyhave edges where the horizontal first back surface 315 m of the firststep section 315 d that is located on the opposite side of the secondrotor core 321 crosses the outer side surface 315 j of the firstmagnetic pole section 315 f formed by the arcuate surfaces. The edge isshaped such that a portion having isosceles right triangular shape incross-section is cut out from this edge to form first coupling surfacef1. The length of two sides between which an oblique side locates in theisosceles right triangle is set to be the same as the thickness in theaxial direction of the first rotor core base 314. Since the outer sidesurfaces 315 j are the arcuate surfaces, the first coupling surfaces f1formed in the first rotor side claw-like magnetic poles 315 are formedas conical surfaces centering on the center axis O.

The first annular auxiliary magnet 341 is bonded and fixed to the firstcoupling surfaces f1 of the first rotor side claw-like magnetic poles315 by an adhesive.

As shown in FIGS. 44 and 46, the first annular auxiliary magnet 341 is apermanent magnet formed by a ferrite magnet formed in a ring shape. Thefirst annular auxiliary magnet 341 is shaped to be isosceles righttriangle in cross-section that is same as a portion having isoscelesright triangular shape in cross-section that is cut out from theabove-described edge. The oblique side of the isosceles right trianglein cross-section forms an inner side surface 341 a of the first annularauxiliary magnet 341.

Therefore, the inner side surface 341 a of the first annular auxiliarymagnet 341 is formed as a conical surface centering on the center axisO. The inner side surface 341 a of the first annular auxiliary magnet341 is bonded and fixed to the first coupling surfaces f1 of the firstrotor side claw-like magnetic poles 315 at a predetermined pitch by anadhesive.

When the first annular auxiliary magnet 341 is bonded and fixed to thefirst rotor side claw-like magnetic poles 315, a radial outer sidesurface 341 b of the first annular auxiliary magnet 341 is flush withthe outer side surface 315 j of the first magnetic pole section 315 f.An axial outer side surface 341 c of the first annular auxiliary magnet341 is flush with the horizontal first back surface 315 m on the countersecond rotor core 321 side of the first step section 315 d.

In this case, the distal end face 325 c of the second magnetic polesection 325 f relatively arranged between the first rotor side claw-likemagnetic poles 315 in the circumferential direction is in contact withan edge portion where the radial outer side surface 341 b and the innerside surface 341 a of the first annular auxiliary magnet 341 cross eachother.

As shown in FIG. 47, in the first annular auxiliary magnet 341,twenty-four first magnet sections 342 equally divided by the number ofthe first rotor side claw-like magnetic poles 315 and the second rotorside claw-like magnetic poles 325 (twenty-four) in the circumferentialdirection are formed.

As shown in FIG. 48, the first annular auxiliary magnet 341 is arrangedwith respect to the first rotor core 311 such that boundaries betweenthe first magnet sections 342 respectively coincide with circumferentialcenter positions of the first magnetic pole sections 315 f of the firstrotor side claw-like magnetic poles 315 or circumferential centerpositions of the second magnetic pole sections 325 f of the second rotorside claw-like magnetic poles 325.

As shown in FIGS. 47 and 48, the first annular auxiliary magnet 341arranged in this way is magnetized in the circumferential direction inthe first magnet sections 342 and magnetized to set the first magneticpole section 315 f sides as N poles and set the second magnetic polesection 325 f sides as S poles in the first magnet sections 342.

That is, the N poles of the first magnet sections 342 are respectivelyarranged at the proximal end portions of the first magnetic polesections 315 f of the first rotor side claw-like magnetic poles 315. TheS poles of the first magnet sections 342 are respectively arranged atthe distal end portions of the second magnetic pole sections 325 f ofthe second rotor side claw-like magnetic poles 325.

Consequently, leakage fluxes (short-circuit fluxes) from the proximalend portions of the first magnetic pole sections 315 f of the N poles tothe distal end portions of the second magnetic pole sections 325 f ofthe S poles decrease.

Second Annular Auxiliary Magnet 351

As shown in FIGS. 45 and 46, the second annular auxiliary magnet 351 isfirmly fixed to a counter first rotor core 311 side of the second rotorcore 321.

More specifically, as shown in FIGS. 44 and 46, the second rotor sideclaw-like magnetic poles 325 of the second rotor core 321 respectivelyhave edges where the horizontal first back surfaces 325 m of the secondstep sections 325 d that is located on the opposite side of the firstrotor core 311 crosses the outer side surfaces 325 j of the secondmagnetic pole sections 325 f formed by the arcuate surfaces. The edge isshaped such that a portion having isosceles right triangular shape incross-section is cut out from this edge to form second coupling surfacesf2. The length of two sides between which an oblique side locates in theisosceles right triangle is set to be the same as the thickness in theaxial direction of the second rotor core base 324. Since the outer sidesurfaces 325 j are the arcuate surfaces, the second coupling surfaces f2formed in the second rotor side claw-like magnetic poles 325 are formedas conical surfaces centering on the center axis O.

The second annular auxiliary magnet 351 is bonded and fixed to thesecond coupling surfaces f2 of the second rotor side claw-like magneticpoles 325 by an adhesive.

As shown in FIGS. 44 and 46, the second annular auxiliary magnet 351 isa permanent magnet formed by a ferrite magnet formed in an annularshape. The second annular auxiliary magnet 351 is shaped to be isoscelesright triangle in cross-section that is same as a portion havingisosceles right triangular shape in cross-section that is cut out fromthe above-described edge. The oblique side of the isosceles righttriangle in cross-section forms an inner side surface 351 a of thesecond annular auxiliary magnet 351.

Therefore, the inner side surface 351 a of the second annular auxiliarymagnet 351 is formed as a conical surface centering on the center axisO. The inner side surface 351 a of the second annular auxiliary magnet351 is bonded and fixed to the second coupling surfaces f2 of the secondrotor side claw-like magnetic poles 325 at a predetermined pitch by anadhesive.

When the second annular auxiliary magnet 351 is bonded and fixed to thesecond rotor side claw-like magnetic poles 325, a radial outer sidesurface 351 b of the second annular auxiliary magnet 351 is flush withthe outer side surface 325 j of the second magnetic pole section 325 f.An axial outer side surface 351 c of the second annular auxiliary magnet351 is flush with the horizontal second back surface 325 m on thecounter first rotor core 311 side of the second step section 325 d.

In this case, the distal end face 315 c of the first magnetic polesection 315 f relatively arranged between the second rotor sideclaw-like magnetic poles 325 in the circumferential direction is incontact with an edge portion where the radial outer side surface 351 band the inner side surface 351 a of the second annular auxiliary magnet351 cross each other.

As shown in FIG. 47, in the second annular auxiliary magnet 351,twenty-four second magnet sections 352 equally divided by the number ofthe first rotor side claw-like magnetic poles 315 and the second rotorside claw-like magnetic poles 325 (twenty-four) in the circumferentialdirection are formed.

As shown in FIG. 48, the second annular auxiliary magnet 351 is arrangedwith respect to the second rotor core 321 such that boundaries betweenthe second magnet sections 352 respectively coincide withcircumferential center positions of the second magnetic pole sections325 f of the second rotor side claw-like magnetic poles 325 orcircumferential center positions of the first magnetic pole sections 315f of the first rotor side claw-like magnetic poles 315.

As shown in FIGS. 47 and 48, the second annular auxiliary magnet 351arranged in this way is magnetized in the circumferential direction inthe second magnet sections 352 and magnetized to set the first magneticpole section 315 f sides as N poles and set the second magnetic polesection 325 f sides as S poles in the second magnet sections 352.

That is, the S poles of the second magnet sections 352 are respectivelyarranged at the proximal end portions of the second magnetic polesections 325 f of the second rotor side claw-like magnetic poles 325.The N poles of the second magnet sections 352 are respectively arrangedat the distal end portions of the first magnetic pole sections 315 f ofthe first rotor side claw-like magnetic poles 315.

Consequently, leakage fluxes (short-circuit fluxes) from the distal endportions of the first magnetic pole sections 315 f of the N poles to theproximal end portions of the second magnetic pole sections 325 f of theS poles decrease.

Stator 303

The stator 303 arranged on the radial outer side of the rotor 302includes, as shown in FIGS. 49 and 50, first and second stator cores 361and 371 and a coil section 381.

First Stator Core 361

As shown in FIG. 50, the first stator core 361 includes a ringplate-like first stator core base 364 formed by an electromagnetic steelplate. In the ring plate-like first stator core base 364, an outercircumferential section thereof is formed to be bent to the secondstator core 371 side to form a first stator side cylindrical wall 364 e.An annular distal end face 364 f of the first stator side cylindricalwall 364 e is opposed to the second stator core 371. The length in theaxial direction of the first stator side cylindrical wall 364 e is halflength of the length in the axial direction of the rotors in therespective phases.

On an inner circumferential surface 364 d of the first stator core base364, twelve first stator side claw-like magnetic poles 365 are projectedto the radial inner side at equal intervals. The distal ends of thefirst stator side claw-like magnetic poles 365 are formed to be bent tothe second stator core 371 side in the axial direction.

In the first stator side claw-like magnetic pole 365, a portionprojecting to the radial inner side from the inner circumferentialsurface 364 d of the first stator core base 364 is referred to as firststator side base section 365 g. A distal end portion bent in the axialdirection is referred to as first stator side magnetic pole section 365h. The first stator side claw-like magnetic pole 365 before the firststator side magnetic pole section 365 h is formed to be bent is formedin a trapezoidal shape tapered toward the distal end when viewed fromthe axial direction.

That is, a shape of the first stator side base section 365 g when viewedfrom the axial direction is a trapezoidal shape smaller in width towardthe radial inner side. A shape of the first stator side magnetic polesection 365 h when viewed from the radial direction is a trapezoidalshape smaller in width toward the distal end. Both circumferential endfaces 365 a and 365 b of the first stator side claw-like magnetic pole365 including the first stator side base section 365 g and the firststator side magnetic pole section 365 h are flat surfaces and are closerto each other toward the distal end.

Consequently, a sectional area of a cross section cut in the axialdirection of the first stator side base section 365 g viewed from theradial direction is smaller toward the radial inner side. A sectionalarea of a cross section cut in the radial direction of the first statorside magnetic pole section 365 h viewed from the axial direction issmaller toward the distal end side.

Note that the first stator side magnetic pole section 365 h formed to bebent in the axial direction has a fan shape in cross-section in thedirection orthogonal to the axial direction. An outer side surface 365 jand an inner side surface 365 k in the radial direction of the firststator side magnetic pole section 365 h are, when viewed from the axialdirection, an arcuate surface concentric with the inner circumferentialsurface 364 d of the first stator core base 364 centering on the centeraxis O.

An angle in the circumferential direction of the first stator side basesections 365 g of the first stator side claw-like magnetic poles 365,that is, an angle formed by the proximal end portions of thecircumferential end faces 365 a and 365 b with respect to the centeraxis O of the rotating shaft (not shown in the figure) is set smallerthan an angle of a gap between the proximal ends of the first statorside base sections 365 g of the first stator side claw-like magneticpoles 365 adjacent to each other.

Second Stator Core 371

As shown in FIG. 50, the second stator core 371 includes a ringplate-like second stator core base 374 formed by an electromagneticsteel plate formed of a material and in a shape same as the material andthe shape of the first stator core base 364. In the ring plate-likesecond stator core base 374, an outer circumferential section thereof isformed to be bent to the first stator core 361 side to form a secondstator side cylindrical wall 374 e. An annular distal end face 374 f ofthe second stator side cylindrical wall 374 e is opposed to the distalend face 364 f of the first stator side cylindrical wall 364 e. Thelength in the axial direction of the second stator side cylindrical wall374 e is half length of the length in the axial direction of the rotorsin the respective phases.

On an inner circumferential surface 374 d of the second stator core base374, twelve second stator side claw-like magnetic poles 375 areprojected to the radial inner side at equal intervals. The distal endsof the second stator side claw-like magnetic poles 375 are formed to bebent to the first stator core 361 side in the axial direction.

In the second stator side claw-like magnetic pole 375, a portionprojecting to the radial inner side from the inner circumferentialsurface 374 d of the second stator core base 374 is referred to assecond stator side base section 375 g. A distal end portion bent in theaxial direction is referred to as second stator side magnetic polesection 375 h. The second stator side claw-like magnetic pole 375 beforethe second stator side magnetic pole section 375 h is formed to be bentis formed in a trapezoidal shape tapered toward the distal end whenviewed from the axial direction.

That is, a shape of the second stator side base section 375 g whenviewed from the axial direction is a trapezoidal shape smaller in widthtoward the radial inner side. A shape of the second stator side magneticpole section 375 h when viewed from the radial direction is atrapezoidal shape smaller in width toward the distal end. Bothcircumferential end faces 375 a and 375 b of the second stator sideclaw-like magnetic pole 375 including the second stator side basesection 375 g and the second stator side magnetic pole section 375 h areflat surfaces and are closer to each other toward the distal end.

Consequently, a sectional area of a cross section cut in the axialdirection of the second stator side base section 375 g viewed from theradial direction is smaller toward the radial inner side. A sectionalarea of a cross section cut in the radial direction of the second statorside magnetic pole section 375 h viewed from the axial direction issmaller toward the distal end side.

Note that the second stator side magnetic pole section 375 h formed tobe bent in the axial direction has a fan shape in cross-section in thedirection orthogonal to the axial direction. An outer side surface 375 jand an inner side surface 375 k in the radial direction of the secondstator side magnetic pole section 375 h are, when viewed from the axialdirection, an arcuate surface concentric with the inner circumferentialsurface 374 d of the second stator core base 374 centering on the centeraxis O.

An angle in the circumferential direction of the second stator side basesections 375 g of the second stator side claw-like magnetic poles 375,that is, an angle formed by the proximal end portions of thecircumferential end faces 375 a and 375 b with respect to the centeraxis O of the rotating shaft (not shown in the figure) is set smallerthan an angle of a gap between the proximal ends of the second statorside base sections 375 g of the second stator side claw-like magneticpoles 375 adjacent to each other.

That is, when the second stator core 371 is formed as explained above,the shape of the second stator core 371 is the same as the shape of thefirst stator core 361. The distal end face 364 f of the first statorside cylindrical wall 364 e and the distal end face 374 f of the secondstator side cylindrical wall 374 e are set in contact with each other.The first and second stator cores 361 and 371 are arranged to be fixedsuch that the second stator side claw-like magnetic poles 375 arerespectively located among the first stator side claw-like magneticpoles 365 when viewed from the axial direction.

In this case, as shown in FIG. 44, the first stator side claw-likemagnetic pole 365 is set in a position where a distal end face 365 c ofthe first stator side magnetic pole section 365 h thereof is flush withan opposed surface 374 a of the second stator core base 374. Similarly,the second stator side claw-like magnetic pole 375 is set in a positionwhere a distal end face 375 c of the second stator side magnetic polesection 375 h thereof is flush with an opposed surface 364 a of thefirst stator core base 364.

Incidentally, an annular space having a square shape in cross-section isformed, which is defined by the opposed surfaces 364 a and 374 a of thefirst and second stator core bases 364 and 374, the innercircumferential surfaces of the first and second stator side cylindricalwalls 364 e and 374 e, and the outer side surfaces 365 j and 375 j ofthe first and second stator side magnetic pole sections 365 h and 375 h.As shown in FIG. 44, the coil section 381 (an annular winding wire 382)is arranged and fixed in the annular space having the square shape incross-section.

Coil Section 381

As shown in FIG. 50, the coil section 381 includes the annular windingwire 382. The annular winding wire 382 is wound around in the annularspace. The first and second stator side claw-like magnetic poles 365 and375 are energized to be different magnetic poles each other at everymoment by feeding a single-phase alternating current to the annularwinding wire 382.

The stator 303 configured as explained above is a stator of a so-calledLundell type (a claw pole type) structure including twenty-four polesthat energize, with the annular winding wire 382 between the first andsecond stator cores 361 and 371, the first and second stator sideclaw-like magnetic poles 365 and 375 to be different magnetic poles eachother at every moment.

Action of the brushless motor 301 configured as explained above isexplained.

When a single-phase alternating current is fed to the annular windingwire 382 of the stator 303, a rotation magnetic field is generated inthe stator 303. The rotor 302 is driven to rotate.

In this case, the first annular auxiliary magnet 341 is firmly fixed tothe counter second rotor core 321 side of the first rotor core 311. Thefirst annular auxiliary magnet 341 is arranged with respect to the firstrotor core 311 such that boundaries among the equally dividedtwenty-four first magnet sections 342 respectively coincide with thecircumferential center positions of the first magnetic pole sections 315f and the circumferential center positions of the second magnetic polesections 325 f.

The first annular auxiliary magnet 341 is magnetized in thecircumferential direction in the first magnet sections 342 andmagnetized to set the first magnetic pole section 315 f sides as N polesand set the second magnetic pole section 325 f sides as S poles in thefirst magnet sections 342.

Therefore, the N poles of the first magnet sections 342 of the firstannular auxiliary magnet 341 are respectively arranged at the proximalend portions of the first magnetic pole sections 315 f that are the Npoles in the magnetic field magnet 331. The S poles of the first magnetsections 342 of the first annular auxiliary magnet 341 are respectivelyarranged at the distal end portions of the second magnetic pole sections325 f that are the S poles in the magnetic field magnet 331.

As a result, leakage fluxes (short-circuit fluxes) from the proximal endportions of the first magnetic pole sections 315 f of the N pole to thedistal end portions of the second magnetic pole sections 325 f of the Spole are reduced by the first magnet sections 342 of the first annularauxiliary magnet 341.

Similarly, the second annular auxiliary magnet 351 is firmly fixed tothe counter first rotor core 311 side of the second rotor core 321. Thesecond annular auxiliary magnet 351 is arranged with respect to thesecond rotor core 321 such that boundaries among the equally dividedtwenty-four second magnet sections 352 respectively coincide with thecircumferential center positions of the second magnetic pole sections325 f and the circumferential center positions of the first magneticpole sections 315 f.

The second annular auxiliary magnet 351 is magnetized in thecircumferential direction in the second magnet sections 352 andmagnetized to set the second magnetic pole section 325 f sides as Spoles and set the first magnetic pole section 315 f sides as N poles inthe second magnet sections 352.

Therefore, the S poles of the second magnet sections 352 of the secondannular auxiliary magnet 351 are respectively arranged at the proximalend portions of the second magnetic pole sections 325 f that are the Spoles in the magnetic field magnet 331. The N poles of the second magnetsections 352 of the second annular auxiliary magnet 351 are respectivelyarranged at the distal end portions of the first magnetic pole sections315 f that are the N poles in the magnetic field magnet 331.

As a result, leakage fluxes (short-circuit fluxes) from the distal endportions of the first magnetic pole sections 315 f of the N poles to theproximal end portions of the second magnetic pole sections 325 f of theS poles are reduced by the second magnet sections 352 of the secondannular auxiliary magnet 351.

As explained above, the first and second annular auxiliary magnets 341and 351 that reduce leakage fluxes (short-circuit fluxes) arerespectively firmly fixed to the first and second rotor cores 311 and321. Therefore, it is possible to realize an increase in an output ofthe brushless motor 301.

An output of the brushless motor 301 firmly fixed with the first andsecond annular auxiliary magnets 341 and 351 in the fourth embodimentand an output of the brushless motor 301 not provided with the first andsecond annular auxiliary magnets 341 and 351 were compared and verified.An induced voltage, which is an element of the output of the brushlessmotor 301, was acquired by an experiment and a result shown in FIG. 51was obtained.

An induced voltage characteristic line Lk in FIG. 51 is an inducedvoltage curve of the brushless motor not provided with the first andsecond annular auxiliary magnets 341 and 351. An induced voltagecharacteristic line L1 in FIG. 51 is an induced voltage curve of thebrushless motor 301 provided with the first and second annular auxiliarymagnets 341 and 351 in this embodiment.

As it is evident from the experiment result, it is seen that a maximumof an induced voltage is about 10% higher in the brushless motor 301provided with the first and second annular auxiliary magnets 341 and 351in this embodiment than in the brushless motor not provided with thefirst and second annular auxiliary magnets 341 and 351.

That is, it is seen that the first and second annular auxiliary magnets341 and 351 contribute to an increase in the output of the brushlessmotor 301.

Advantages of the fourth embodiment are explained below.

(8) Leakage fluxes (short-circuit fluxes) from the proximal end portionsof the first magnetic pole sections 315 f of the N poles to the distalend portions of the second magnetic pole sections 325 f of the S polescan be reduced by the first magnet sections 342 of the first annularauxiliary magnet 341. It is possible to attain an increase in the outputof the brushless motor 301.

(9) According to this embodiment, leakage fluxes (short-circuit fluxes)from the distal end portions of the first magnetic pole sections 315 fof the N poles to the proximal end portions of the second magnetic polesections 325 f of the S poles can be reduced by the second magnetsections 352 of the second annular auxiliary magnet 351. It is possibleto attain an increase in the output of the brushless motor 301.

(10) According to this embodiment, in the first annular auxiliary magnet341 firmly fixed to the first rotor core 311, the first magnet sections342 opposed to the second rotor side claw-like magnetic poles 325 areset in contact with the distal end faces 325 c of the second magneticpole sections 325 f of the second rotor side claw-like magnetic poles325. Therefore, it is possible to further reduce the leakage fluxes (theshort-circuit fluxes).

(11) In this embodiment, in the second annular auxiliary magnet 351firmly fixed to the second rotor core 321, the second magnet sections352 opposed to the first rotor side claw-like magnetic poles 315 are setin contact with the distal end faces 315 c of the first magnetic polesections 315 f of the first rotor side claw-like magnetic poles 315.Therefore, it is possible to further reduce the leakage fluxes (theshort-circuit fluxes).

(12) According to this embodiment, the first and second annularauxiliary magnets 341 and 351 are annular bodies. Therefore, the firstand second annular auxiliary magnets 341 and 351 can be coupled andfirmly fixed to the outer circumferential sections of the first andsecond rotor side claw-like magnetic poles 315 and 325 at a time. It iseasy to assemble the first and second annular auxiliary magnets 341 and351 to the first and second rotor cores 311 and 321. Moreover, it isunlikely that the first and second annular auxiliary magnets 341 and 351project in the radial direction with a centrifugal force involved in therotation of the rotor 302.

(13) According to this embodiment, the first rotor side claw-likemagnetic poles 315 respectively have the edges where the horizontalfirst back surface 315 m of the first step sections 315 d crosses theouter side surface 315 j of the first magnetic pole section 315 f. Theedge is shaped such that a portion having isosceles right triangularshape in cross-section is cut out from the edge to form the firstcoupling surface f1. The first annular auxiliary magnet 341 havingisosceles right triangular shape in cross-section is firmly fixed to thefirst coupling surfaces f1. In this case, the radial outer side surface341 b of the first annular auxiliary magnet 341 is set flush with theouter side surfaces 315 j of the first magnetic pole sections 315 f. Theaxial outer side surface 341 c of the first annular auxiliary magnet 341is set flush with the first back surfaces 315 m of the first stepsections 315 d.

Similarly, the second rotor side claw-like magnetic poles 325respectively have the edges where the horizontal second back surface 325m of the second step section 325 d crosses the outer side surface 325 jof the second magnetic pole section 325 f. The edge is shaped such thata portion having isosceles right triangular shape in cross-section iscut out form this edge to form the second coupling surfaces f2. Thesecond annular auxiliary magnet 351 having isosceles right triangularshape in cross-section is firmly fixed to the second coupling surfacesf2. In this case, the radial outer side surface 351 b of the secondannular auxiliary magnet 351 is set flush with the outer side surfaces325 j of the second magnetic pole sections 325 f. The axial outer sidesurface 351 c of the second annular auxiliary magnet 351 is set flushwith the second back surfaces 325 m of the second step sections 325 d.

Consequently, the overall shape of the rotor 302 is not increased in theaxial direction and the radial direction by providing the first andsecond annular auxiliary magnets 341 and 351. That is, it is possible toattain a reduction in the size of the rotor 302.

Note that, as shown in FIG. 52, in the fourth embodiment, a magneticdetector 391 including a Hall IC may be provided in a motor housing,not-shown, to be opposed to the first annular auxiliary magnet 341 at afixed interval to detect a rotating position, the number of revolutions,and the like of the rotor 302 (the motor 301).

More specifically, the magnetic detector 391 is arranged in the motorhousing such that, when the first annular auxiliary magnet 341 rotatestogether with the rotor 302, the first magnet sections 342 of the firstannular auxiliary magnet 341 pass the front of the magnetic detector391.

According to the rotation of the rotor 302, the magnetic detector 391detects leakage fluxes of the first magnet sections 342, which pass thefront of the magnetic detector 391, and outputs a signal of thedetection to a not-shown control circuit. The not-shown control circuitcalculates a rotation angle (a rotating position) of the rotor 302 andcalculates the number of revolutions on the basis of the detectionsignal output from the magnetic detector 391.

FIG. 53 shows a detection waveform B1 of the magnetic detector 391 thatdetects a leakage flux of the first annular auxiliary magnet 341provided in the brushless motor 301 in the fourth embodiment and adetection waveform Bk of the magnetic detector 391 that detects aleakage flux from the brushless motor 301 not provided with the firstand second annular auxiliary magnets 341 and 351. As it is evident fromFIG. 53, a width of change is larger in the detection waveform B1 of themagnetic detector 391 that detects a leakage flux of the first annularauxiliary magnet 341 in the fourth embodiment. Therefore, it is possibleto perform highly accurate rotation detection. Further, since the firstannular auxiliary magnet 341 is also used as a member to be detected fordetection of a rotation angle and the number of revolutions, it ispossible to attain a reduction in the number of components.

A motor according to a fifth embodiment is explained below withreference to FIGS. 54 to 57.

This embodiment is different in relative positions in thecircumferential direction of the first and second annular auxiliarymagnets 341 and 351 in the fourth embodiment with respect to the firstand second rotor side claw-like magnetic poles 315 and 325 andmagnetization directions of the first and second magnet sections 342 and352. Therefore, for convenience of explanation, the differences areexplained in detail.

As shown in FIG. 54, the first annular auxiliary magnet 341, in whichthe twenty-four first magnet sections 342 are formed in thecircumferential direction, is arranged with respect to the first rotorcore 311 such that the boundaries between the first magnet sections 342respectively coincide with circumferential intermediate positions of thefirst rotor side claw-like magnetic poles 315 and the second rotor sideclaw-like magnetic poles 325.

The first magnet sections 342 of the first annular auxiliary magnet 341are magnetized in the axial direction unlike the fourth embodiment. Morespecifically, the first magnet sections 342 opposed to the first rotorside claw-like magnetic poles 315 are magnetized to set the first rotorcore 311 sides as S poles and set the second rotor core 321 sides as Npoles in the axial direction. The first magnet sections 342 opposed tothe second rotor side claw-like magnetic poles 325 are magnetized to setthe first rotor core 311 sides as N poles and set the second rotor core321 sides as S poles in the axial direction.

Consequently, leakage fluxes from the proximal end portions of the firstmagnetic pole sections 315 f to the distal end portions of the secondmagnetic pole sections 325 f decrease.

On the other hand, as shown in FIG. 54, the second annular auxiliarymagnet 351, in which the twenty-four second magnet sections 352 areformed in the circumferential direction, is arranged with respect to thefirst rotor core 311 such that the boundaries between the second magnetsections 352 respectively coincide with circumferential intermediatepositions of the first rotor side claw-like magnetic poles 315 and thesecond rotor side claw-like magnetic poles 325.

The second magnet sections 352 of the second annular auxiliary magnet351 are magnetized in the axial direction unlike the fourth embodiment.More specifically, the second magnet sections 352 opposed to the secondrotor side claw-like magnetic poles 325 are magnetized to set the secondrotor core 321 sides as N poles and set the first rotor core 311 sidesas S poles in the axial direction. The second magnet sections 352opposed to the first rotor side claw-like magnetic poles 315 aremagnetized to set the second rotor core 321 sides as S poles and set thefirst rotor core 311 sides as N poles in the axial direction.

Consequently, leakage fluxes from the distal end portions of the firstmagnetic pole sections 315 f to the proximal end portions of the secondmagnetic pole sections 325 f decrease.

Action of the brushless motor 301 configured as explained above isexplained.

The first magnet sections 342 of the first annular auxiliary magnet 341are magnetized in the axial direction. The first magnet sections 342opposed to the first rotor side claw-like magnetic poles 315 aremagnetized to set the first rotor core 311 sides as S poles and set thesecond rotor core 321 sides as N poles in the axial direction. The firstmagnet sections 342 opposed to the second rotor side claw-like magneticpoles 325 are magnetized to set the first rotor core 311 sides as Npoles and set the second rotor core 321 sides as S poles in the axialdirection.

Therefore, leakage fluxes (short-circuit fluxes) from the proximal endportions of the first magnetic pole sections 315 f of the N poles to thedistal end portions of the second magnetic pole sections 325 f of the Spoles are reduced by the first magnet sections 342 of the first annularauxiliary magnet 341.

On the other hand, the second magnet sections 352 of the second annularauxiliary magnet 351 are magnetized in the axial direction. The secondmagnet sections 352 opposed to the second rotor side claw-like magneticpoles 325 are magnetized to set the second rotor core 321 sides as Npoles and set the first rotor core 311 sides as S poles. The secondmagnet sections 352 opposed to the first rotor side claw-like magneticpoles 315 are magnetized to set the second rotor core 321 sides as Spoles and set the first rotor core 311 sides as N poles.

Therefore, leakage fluxes (short-circuit fluxes) from the distal endportions of the first magnetic pole sections 315 f of the N poles to theproximal end portions of the second magnetic pole sections 325 f of theS poles are reduced by the second magnet sections 352 of the secondannular auxiliary magnet 351.

As explained above, the first and second annular auxiliary magnets 341and 351 that reduce leakage fluxes (short-circuit fluxes) arerespectively firmly fixed to the first and second rotor cores 311 and321. Therefore, it is possible to attain an increase in an output of thebrushless motor 301.

An output of the brushless motor 301 firmly fixed with the first andsecond annular auxiliary magnets 341 and 351 in the fifth embodiment andan output of the brushless motor 301 not provided with the first andsecond annular auxiliary magnets 341 and 351 were compared and verified.As in the fourth embodiment, an induced voltage, which is an element ofthe output of the brushless motor 301, was acquired by an experiment anda result shown in FIG. 55 was obtained.

An induced voltage characteristic line Lk in FIG. 55 is an inducedvoltage curve of the brushless motor not provided with the first andsecond annular auxiliary magnets 341 and 351. An induced voltagecharacteristic line L2 in FIG. 55 is an induced voltage curve of thebrushless motor 301 provided with the first and second annular auxiliarymagnets 341 and 351 in the fifth embodiment.

As it is evident from the experiment result, it is seen that a maximumof an induced voltage is about 7% higher in the brushless motor 301provided with the first and second annular auxiliary magnets 341 and 351in this embodiment than in the brushless motor not provided with thefirst and second annular auxiliary magnets 341 and 351.

That is, it is seen that the first and second annular auxiliary magnets341 and 351 in this embodiment contribute to an increase in the outputof the brushless motor 301.

The fifth embodiment has advantages explained below in addition to theadvantages (12) and (13) explained in the fourth embodiment.

(14) According to this embodiment, leakage fluxes (short-circuit fluxes)from the proximal end portions of the first magnetic pole sections 315 fof the N poles to the distal end portions of the second magnetic polesections 325 f of the S poles can be reduced by the first magnetsections 342 of the first annular auxiliary magnet 341. It is possibleto attain an increase in the output of the brushless motor 301.

(15) According to this embodiment, leakage fluxes (short-circuit fluxes)from the distal end portions of the first magnetic pole sections 315 fof the N poles to the proximal end portions of the second magnetic polesections 325 f of the S poles can be reduced by the second magnetsections 352 of the second annular auxiliary magnet 351. It is possibleto attain an increase in the output of the brushless motor 301.

(16) According to this embodiment, in the first annular auxiliary magnet341 firmly fixed to the first rotor core 311, the first magnet sections342 opposed to the second rotor side claw-like magnetic poles 325 areset in contact with the distal end faces 325 c of the second magneticpole sections 325 f of the second rotor side claw-like magnetic poles325. Therefore, it is possible to further reduce the leakage fluxes (theshort-circuit fluxes).

(17) In this embodiment, in the second annular auxiliary magnet 351firmly fixed to the second rotor core 321, the second magnet sections352 opposed to the first rotor side claw-like magnetic poles 315 are setin contact with the distal end faces 315 c of the first magnetic polesections 315 f of the first rotor side claw-like magnetic poles 315.Therefore, it is possible to further reduce the leakage fluxes (theshort-circuit fluxes).

Note that, as shown in FIG. 56, in the fifth embodiment, the magneticdetector 391 including a Hall IC may be provided in a not-shown motorhousing to be opposed to the first annular auxiliary magnet 341 at afixed interval to perform rotation detection of a rotating position, thenumber of revolutions, and the like of the rotor 302 (the motor 301).

More specifically, the magnetic detector 391 is arranged in the motorhousing such that, when the first annular auxiliary magnet 341 rotatestogether with the rotor 302, the first magnet sections 342 of the firstannular auxiliary magnet 341 pass the front of the magnetic detector391.

According to the rotation of the rotor 302, the magnetic detector 391detects leakage fluxes of the first magnet sections 342 at the time whenthe first magnet section 342 is passing the front of the magneticdetector 391 and outputs a signal of the detection to a not-showncontrol circuit. The control circuit, not-shown, calculates a rotationangle (a rotating position) of the rotor 302 and calculates the numberof revolutions on the basis of the detection signal output from themagnetic detector 391.

FIG. 57 shows a detection waveform B2 of the magnetic detector 391 thatdetects a leakage flux of the first annular auxiliary magnet 341provided in the brushless motor 301 in the fifth embodiment and adetection waveform Bk of the magnetic detector 391 that detects aleakage flux from the brushless motor 301 not provided with the firstand second annular auxiliary magnets 341 and 351. As it is evident fromFIG. 57, a waveform is more rectangular in the detection waveform B2 ofthe magnetic detector 391 that detects a leakage flux of the firstannular auxiliary magnet 341 in the fifth embodiment. Therefore, it ispossible to perform more highly accurate rotation detection. Further,since the first annular auxiliary magnet 341 is also used as a member tobe detected for detection of a rotation angle and the number ofrevolutions, it is possible to attain a reduction in the number ofcomponents.

A motor according to a sixth embodiment is explained below withreference to FIGS. 58 and 59.

This embodiment is different in magnetization directions from themagnetization directions of the first and second magnet sections 342 and352 of the first and second annular auxiliary magnets 341 and 351explained in the fourth embodiment. Therefore, for convenience ofexplanation, the differences are explained in detail.

In the first annular auxiliary magnet 341, as in the fourth embodiment,the twenty-four first magnet sections 342 are formed in thecircumferential direction. As in the fourth embodiment, the firstannular auxiliary magnet 341 is arranged with respect to the first rotorcore 311 such that boundaries between the first magnet sections 342respectively coincide with circumferential center positions of the firstmagnetic pole sections 315 f of the first rotor side claw-like magneticpoles 315 or circumferential center positions of the second magneticpole sections 325 f of the second rotor side claw-like magnetic poles325.

As shown in FIG. 58, the first magnet sections 342 are magnetized in thecircumferential direction. More specifically, unlike the fourthembodiment, the first magnet sections 342 are magnetized to set thefirst magnetic pole section 315 f sides as S poles and set the secondmagnetic pole section 325 f sides as N poles in the circumferentialdirection.

That is, the S poles of the first magnet sections 342 are respectivelyarranged at the proximal end portions of the first magnetic polesections 315 f of the first rotor side claw-like magnetic poles 315. TheN poles of the first magnet sections 342 are respectively arranged atthe distal end portions of the second magnetic pole sections 325 f ofthe second rotor side claw-like magnetic poles 325.

Consequently, conversely to the fourth embodiment, leakage fluxes(short-circuit fluxes) from the proximal end portions of the firstmagnetic pole sections 315 f of the N poles to the distal end portionsof the second magnetic pole sections 325 f of the S poles are increased.

On the other hand, as shown in FIG. 58, the second magnet sections 352are magnetized in the circumferential direction. More specifically,unlike the fourth embodiment, the second magnet sections 352 aremagnetized to set the first magnetic pole section 315 f sides as S polesand set the second magnetic pole section 325 f sides as N poles in thecircumferential direction.

That is, at the proximal end portions of the second magnetic polesections 325 f of the second rotor side claw-like magnetic poles 325,the N poles of the second magnet sections 352 are respectively arranged.At the distal end portions of the first magnetic pole sections 315 f ofthe first rotor side claw-like magnetic poles 315, the S poles of thesecond magnet sections 352 are respectively arranged.

Consequently, conversely to the fourth embodiment, leakage fluxes(short-circuit fluxes) from the distal end portions of the firstmagnetic pole sections 315 f of the N poles to the proximal end portionsof the second magnetic pole sections 325 f of the S poles are increased.

Action of the brushless motor 301 configured as explained above isexplained.

In the first annular auxiliary magnet 341, the first magnet sections 342are magnetized to set the first magnetic pole section 315 f sides as Spoles and set the second magnetic pole sections 325 f sides as N poles.Consequently, the S poles of the first magnet sections 342 arerespectively arranged at the proximal end portions of the first magneticpole sections 315 f that are the N poles in the magnetic field magnets331. The N poles of the first magnet sections 342 are respectivelyarranged at the distal end portions of the second magnetic pole sections325 f that are the S poles in the magnetic field magnets 331.

As a result, leakage fluxes (short-circuit fluxes) from the proximal endportions of the first magnetic pole sections 315 f of the N poles to thedistal end portions of the second magnetic pole sections 325 f of the Spoles are increased by the first magnet sections 342 of the firstannular auxiliary magnet 341.

On the other hand, in the second annular auxiliary magnet 351, thesecond magnet sections 352 are magnetized to set the second magneticpole section 325 f sides as N poles and set the first magnetic polesection 315 f sides as S poles. Consequently, the N poles of the secondmagnet sections 352 are respectively arranged at the proximal endportions of the second magnetic pole sections 325 f that are the S polesin the magnetic field magnets 331. The S poles of the second magnetsections 352 are respectively arranged at the distal end portions of thefirst magnetic pole sections 315 f that are the N poles in the magneticfield magnets 331.

As a result, leakage fluxes (short-circuit fluxes) from the distal endportions of the first magnetic pole sections 315 f of the N poles to theproximal end portions of the second magnetic pole sections 325 f of theS poles are increased by the second magnet sections 352 of the secondannular auxiliary magnet 351.

As explained above, the first and second annular auxiliary magnets 341and 351 that increase leakage fluxes (short-circuit fluxes) arerespectively firmly fixed to the first and second rotor cores 311 and321. Therefore, it is possible to realize an increase in the number ofrevolutions of the brushless motor 301.

That is, by actively increasing leakage fluxes (short-circuit fluxes),the brushless motor 301 in the sixth embodiment can generate a so-calledfield weakening effect in the first and second rotor side claw-likemagnetic poles 315 and 325 of the rotor 302 and increase the number ofrevolutions more than the brushless motor 301 in the fourth embodiment.

An output of the brushless motor 301 firmly fixed with the first andsecond annular auxiliary magnets 341 and 351 in the sixth embodiment andan output of the brushless motor 301 firmly fixed with the first andsecond annular auxiliary magnets 341 and 351 in the fourth embodimentwere compared and verified. An induced voltage, which is an element ofthe output of the brushless motor 301, was acquired by an experiment anda result shown in FIG. 59 was obtained.

An induced voltage characteristic line L1 in FIG. 59 is an inducedvoltage curve of the brushless motor provided with the first and secondannular auxiliary magnets 341 and 351 in the fourth embodiment. Aninduced voltage characteristic line L3 in FIG. 59 is an induced voltagecurve of the brushless motor 301 provided with the first and secondannular auxiliary magnets 341 and 351 in the sixth embodiment.

As it is evident from the experiment result, it is seen that a maximumof an induced voltage can be reduced about 21% by the field weakeningeffect in the brushless motor 301 provided with the first and secondannular auxiliary magnets 341 and 351 in this embodiment compared within the brushless motor 301 provided with the first and second annularauxiliary magnets 341 and 351 in the fourth embodiment.

The sixth embodiment has advantages explained below in addition to theadvantages (12) and (13) explained in the fourth embodiment.

(18) According to this embodiment, leakage fluxes (short-circuit fluxes)from the proximal end portions of the first magnetic pole sections 315 fof the N poles to the distal end portions of the second magnetic polesections 325 f of the S poles can be increased by the first magnetsections 342 of the first annular auxiliary magnet 341. It is possibleto drive the brushless motor 301 at a high number of revolutions.

(19) According to this embodiment, leakage fluxes (short-circuit fluxes)from the distal end portions of the first magnetic pole sections 315 fof the N poles to the proximal end portions of the second magnetic polesections 325 f of the S poles can be increased by the second magnetsections 352 of the second annular auxiliary magnet 351. It is possibleto drive the brushless motor 301 at a high number of revolutions.

(20) According to this embodiment, in the first annular auxiliary magnet341 firmly fixed to the first rotor core 311, the first magnet sections342 opposed to the second rotor side claw-like magnetic poles 325 areset in contact with the distal end faces 325 c of the second magneticpole sections 325 f of the second rotor side claw-like magnetic poles325. Therefore, it is possible to further increase the leakage fluxes(the short-circuit fluxes).

(21) In this embodiment, in the second annular auxiliary magnet 351firmly fixed to the second rotor core 321, the second magnet sections352 opposed to the first rotor side claw-like magnetic poles 315 are setin contact with the distal end faces 315 c of the first magnetic polesections 315 f of the first rotor side claw-like magnetic poles 315.Therefore, it is possible to further increase the leakage fluxes (theshort-circuit fluxes).

A motor according to a seventh embodiment is explained with reference toFIGS. 60 to 63.

This embodiment is different in magnetization directions from themagnetization directions of the first and second magnet sections 342 and352 of the first and second annular auxiliary magnets 341 and 351explained in the fifth embodiment. Therefore, for convenience ofexplanation, the differences are explained in detail.

As shown in FIG. 60, in the first annular auxiliary magnet 341, as inthe fifth embodiment, the first magnet sections 342 are magnetized inthe axial direction. Unlike the fifth embodiment, the first magnetsections 342 opposed to the first rotor side claw-like magnetic poles315 are magnetized to set the first rotor core 311 sides as N poles andset the second rotor core 321 sides as S poles in the axial direction.The first magnet sections 342 opposed to the second rotor side claw-likemagnetic poles 325 are magnetized to set the first rotor core 311 sidesas S poles and set the second rotor core 321 sides as N poles in theaxial direction.

Therefore, leakage fluxes (short-circuit fluxes) from the proximal endportions of the first magnetic pole sections 315 f of the N poles to thedistal end portions of the second magnetic pole sections 325 f of the Spoles are increased by the first magnet sections 342 of the firstannular auxiliary magnet 341.

On the other hand, as shown in FIG. 60, in the second annular auxiliarymagnet 351, as in the fifth embodiment, the second magnet sections 352are magnetized in the axial direction. Unlike the fifth embodiment, thesecond magnet sections 352 opposed to the second rotor side claw-likemagnetic poles 325 are magnetized to set the second rotor core 321 sidesas S poles and set the first rotor core 311 sides as N poles in theaxial direction. The second magnet sections 352 opposed to the firstrotor side claw-like magnetic poles 315 are magnetized to set the secondrotor core 321 sides as N poles and set the first rotor core 311 sidesas S poles in the axial direction.

Therefore, leakage fluxes (short-circuit fluxes) from the distal endportions of the first magnetic pole sections 315 f of the N poles to theproximal end portions of the second magnetic pole sections 325 f of theS poles are increased by the second magnet sections 352 of the secondannular auxiliary magnet 351.

Action of the brushless motor 301 configured as explained above isexplained.

In the first annular auxiliary magnet 341, the first magnet sections 342opposed to the first rotor side claw-like magnetic poles 315 aremagnetized to set the first rotor core 311 sides as N poles and set thesecond rotor core 321 sides as S poles in the axial direction. The firstmagnet sections 342 opposed to the second rotor side claw-like magneticpoles 325 are magnetized to set the first rotor core 311 side as S polesand set the second rotor core 321 sides as N poles in the axialdirection.

Therefore, leakage fluxes (short-circuit fluxes) from the proximal endportions of the first magnetic pole sections 315 f of the N poles to thedistal end portions of the second magnetic pole sections 325 f of the Spoles are increased by the first magnet sections 342 of the firstannular auxiliary magnet 341.

On the other hand, in the second annular auxiliary magnet 351, thesecond magnet sections 352 opposed to the second rotor side claw-likemagnetic poles 325 are magnetized to set the second rotor core 321 sidesas S poles and set the first rotor core 311 sides as N poles in theaxial direction. The second magnet sections 352 opposed to the firstrotor side claw-like magnetic poles 315 are magnetized to set the secondrotor core 321 side as N poles and set the first rotor core 311 sides asS poles in the axial direction.

Therefore, leakage fluxes (short-circuit fluxes) from the distal endportions of the first magnetic pole sections 315 f of the N poles to theproximal end portions of the second magnetic pole sections 325 f of theS poles are increased by the second magnet sections 352 of the secondannular auxiliary magnet 351.

As explained above, the first and second annular auxiliary magnets 341and 351 that actively increase leakage fluxes (short-circuit fluxes) arerespectively firmly fixed to the first and second rotor cores 311 and321. Therefore, it is possible to increase the number of revolutions ofthe brushless motor 301.

That is, by actively increasing leakage fluxes (short-circuit fluxes),the brushless motor 301 in the seventh embodiment can generate aso-called field weakening effect in the first and second rotor sideclaw-like magnetic poles 315 and 325 of the rotor 302 and increase thenumber of revolutions more than the brushless motor 301 in the sixthembodiment.

An output of the brushless motor 301 firmly fixed with the first andsecond annular auxiliary magnets 341 and 351 in the seventh embodimentand an output of the brushless motor 301 firmly fixed with the first andsecond annular auxiliary magnets 341 and 351 in the fifth embodimentwere compared and verified. An induced voltage, which is an element ofthe output of the brushless motor 301, was acquired by an experiment anda result shown in FIG. 61 was obtained.

An induced voltage characteristic line L2 in FIG. 61 is an inducedvoltage curve of the brushless motor provided with the first and secondannular auxiliary magnets 341 and 351 in the fifth embodiment. Aninduced voltage characteristic line L4 in FIG. 61 is an induced voltagecurve of the brushless motor 301 provided with the first and secondannular auxiliary magnets 341 and 351 in the seventh embodiment.

As it is evident from the experiment result, it is seen that a maximumof an induced voltage can be reduced about 13% by the field weakeningeffect in the brushless motor 301 provided with the first and secondannular auxiliary magnets 341 and 351 in this embodiment compared within the brushless motor 301 provided with the first and second annularauxiliary magnets 341 and 351 in the fifth embodiment.

The seventh embodiment has advantages explained below in addition to theadvantages (12) and (13) explained in the fourth embodiment.

(22) According to this embodiment, leakage fluxes (short-circuit fluxes)from the proximal end portions of the first magnetic pole sections 315 fof the N poles to the distal end portions of the second magnetic polesections 325 f of the S poles can be increased by the first magnetsections 342 of the first annular auxiliary magnet 341. It is possibleto drive the brushless motor 301 at a high number of revolutions.

(23) According to this embodiment, leakage fluxes (short-circuit fluxes)from the distal end portions of the first magnetic pole sections 315 fof the N poles to the proximal end portions of the second magnetic polesections 325 f of the S poles can be increased by the second magnetsections 352 of the second annular auxiliary magnet 351. It is possibleto drive the brushless motor 301 at a high number of revolutions.

(24) According to this embodiment, in the first annular auxiliary magnet341 firmly fixed to the first rotor core 311, the first magnet sections342 opposed to the second rotor side claw-like magnetic poles 325 areset in contact with the distal end faces 325 c of the second magneticpole sections 325 f of the second rotor side claw-like magnetic poles325. Therefore, it is possible to further increase the leakage fluxes(the short-circuit fluxes).

(25) According to this embodiment, in the second annular auxiliarymagnet 351 firmly fixed to the second rotor core 321, the second magnetsections 352 opposed to the first rotor side claw-like magnetic poles315 are set in contact with the distal end faces 315 c of the firstmagnetic pole sections 315 f of the first rotor side claw-like magneticpoles 315. Therefore, it is possible to further increase the leakagefluxes (the short-circuit fluxes).

Note that, as shown in FIG. 62, in the seventh embodiment, the magneticdetector 391 including a Hall IC may be provided in a not-shown motorhousing to be opposed to the first annular auxiliary magnet 341 at afixed interval to perform rotation detection of a rotating position, thenumber of revolutions, and the like of the rotor 302 (the motor 301).

More specifically, the magnetic detector 391 is arranged in the motorhousing such that, when the first annular auxiliary magnet 341 rotatestogether with the rotor 302, the first magnet sections 342 of the firstannular auxiliary magnet 341 pass the front of the magnetic detector391.

According to the rotation of the rotor 302, the magnetic detector 391detects leakage fluxes of the first magnet sections 342 at the time whenthe first magnet sections 342 are passing the front of the magneticdetector 391 and outputs a signal of the detection to a not-showncontrol circuit. The not-shown control circuit calculates a rotationangle (a rotating position) of the rotor 302 and calculates the numberof revolutions on the basis of the detection signal output from themagnetic detector 391.

FIG. 63 shows a detection waveform B4 of the magnetic detector 391 thatdetects a leakage flux of the first annular auxiliary magnet 341provided in the brushless motor 301 in the seventh embodiment and adetection waveform B2 of the magnetic detector 391 that detects aleakage flux of the first annular auxiliary magnet 341. As it is evidentfrom FIG. 63, the detection waveform B4 of the magnetic detector 391that detects a leakage flux of the first annular auxiliary magnet 341 inthe seventh embodiment is a rectangular waveform having a larger widthof change. Therefore, it is possible to perform highly accurate rotationdetection. Further, since the first annular auxiliary magnet 341 is alsoused as a member to be detected for detection of a rotation angle andthe number of revolutions, it is possible to attain a reduction in thenumber of components.

The fourth to seventh embodiments may be changed as explained below.

The first and second annular auxiliary magnets 341 and 351 in the fourthto seventh embodiments have the isosceles right triangular shape incross-section. However, the first and second annular auxiliary magnets341 and 351 may have right triangular shape or square shape incross-section.

In the fourth to seventh embodiments, the brushless motor 301 includesthe rotor 302 arranged on the inner side of the stator 303 of theLundell type in which the first stator side claw-like magnetic poles 365and the second stator side claw-like magnetic pole 375 are alternatelyarranged in the circumferential direction.

The brushless motor 301 may be applied to a motor in which the rotor 302in the embodiments is arranged on the inner side of a stator that is notthe Lundell type.

The single-phase brushless motor 301 in the fourth to seventhembodiments may be applied to a three-phase brushless motor M in whichthree brushless motors 301 are stacked in the axial direction. That is,as shown in FIG. 64, the three-phase brushless motor M is a brushlessmotor in which the three brushless motors 301, that is, the U-phasemotor section Mu, the V-phase motor section Mv, and the W-phase motorsection Mw are stacked in order.

As shown in FIG. 65, in a three-phase rotor 302M of the three-phasebrushless motor M, three single-phase rotors 302, that is, a U-phaserotor 302 u, a V-phase rotor 302 v, and a W-phase rotor 302 w arestacked in order from the top.

On the other hand, as shown in FIG. 66, in a three-phase stator 303M ofthe three-phase brushless motor M, three single-phase stators 303, thatis, a U-phase stator 303 u, a V-phase stator 303 v, and a W-phase stator303 w are stacked in order from the top. A U-phase current ofthree-phase currents is fed to the U-phase stator 303 u. A V-phasecurrent of the three-phase currents is fed to the V-phase stator 303 v.A W-phase current of the three-phase currents is fed to the W-phasestator 303 w.

Note that, in the three-phase rotor 302M, the U-phase rotor 302 u, theV-phase rotor 302 v, and the W-phase rotor 302 w may be stacked andarranged to be shifted 5 degrees in the mechanical angle (60 degrees inthe electrical angle) from one another.

More specifically, as shown in FIG. 65, the V-phase rotor 302 v isfirmly fixed to the rotating shaft to be shifted 5 degrees in themechanical angle (60 degrees in the electrical angle) with respect tothe U-phase rotor 302 u in the counterclockwise direction centering onthe center axis O of the rotating shaft when viewed from the U-phaserotor 302 u. The W-phase rotor 302 w is firmly fixed to the rotatingshaft to be shifted 5 degrees in the mechanical angle (60 degrees in theelectrical angle) with respect to the V-phase rotor 302 v in thecounterclockwise direction centering on the center axis O of therotating shaft when viewed from the V-phase rotor 302 v.

Similarly, in the three-phase stator 303M, the U-phase stator 303 u, theV-phase stator 303 v, and the W-phase stator 303 w may be stacked andarranged to be shifted 5 degrees in the mechanical angle (60 degrees inthe electrical angle) from one another.

More specifically, as shown in FIG. 66, the V-phase stator 303 v isfirmly fixed to the motor housing to be shifted 5 degrees in themechanical angle (60 degrees in the electrical angle) with respect tothe U-phase stator 303 u in the clockwise direction centering on thecenter axis O when viewed from the U-phase stator 303 u. The W-phasestator 303 w is firmly fixed to the motor housing to be shifted 5degrees in the mechanical angle (60 degrees in the electrical angle)with respect to the V-phase stator 303 v in the clockwise direction whenviewed from the V-phase stator 303 v.

Note that, similarly, the brushless motor 301 may be applied to athree-phase motor in which the rotor 302M for three phases configured byapplying the rotor 302 in the fourth to seventh embodiments is arrangedon the inner side of a stator for three phases that is not the Lundelltype.

In the fourth to seventh embodiments, the number of the first and secondrotor side claw-like magnetic poles 315 and 325 of the first and secondrotor cores 311 and 321 is twelve. However, the number may be changed asappropriate. Similarly, the number of the first and second stator sideclaw-like magnetic poles 365 and 375 of the first and second statorcores 361 and 371 is twelve. However, it goes without saying that thenumber may be changed as appropriate.

In the fourth to seventh embodiments, the magnetic field magnets 331 andthe first and second annular auxiliary magnets 341 and 351 are formed bythe ferrite magnet. However, the magnetic field magnets 331 and thefirst and second annular auxiliary magnets 341 and 351 may be formed byother permanent magnets such as a neodymium magnet. Naturally, thesekinds of permanent magnets may be combined as appropriate.

In the fourth to seventh embodiments, the first annular auxiliary magnet341 is set in contact with the distal end faces 325 c of the secondmagnetic pole sections 325 f. The second annular auxiliary magnet 351 isset in contact with the distal end faces 315 c of the first magneticpole sections 315 f. However, the first and second annular auxiliarymagnets 341 and 351 may be arranged to be opposed to the distal endfaces 325 c and 315 c in the vicinities thereof.

In the fourth to seventh embodiments, in detecting the rotation of themotor 301, the magnetic detector 391 detects the first magnet sections342 of the first annular auxiliary magnet 341. However, the magneticdetector 391 may detect the second magnet sections 352 of the secondannular auxiliary magnet 351.

In the sixth embodiment, rotation detection of the motor 301 by themagnetic detector 391 is not explained. However, it goes without sayingthat the rotation detection of the motor 301 can be performed in thesame manner as in the fourth embodiment.

Technical ideas that can be grasped from the fourth to seventhembodiments and other examples are additionally explained below.

(E) The first magnet sections of the first annular auxiliary magnet aremagnetized in the circumferential direction. The second magnet sectionsof the second annular auxiliary magnet are magnetized in thecircumferential direction.

(F) The first annular auxiliary magnet is fixed to the first rotor coresuch that boundaries that divide the first magnet sections respectivelycoincide with circumferential center positions of the first claw-likemagnetic poles or circumferential center positions of the secondclaw-like magnetic poles. The second annular auxiliary magnet is fixedto the second rotor core such that boundaries that divide the secondmagnet sections respectively coincide with the circumferential centerpositions of the first claw-like magnetic poles or the circumferentialcenter positions of the second claw-like magnetic poles.

(G) The first magnet sections of the first annular auxiliary magnet aremagnetized to set boundary sides coinciding with the circumferentialcenter positions of the first claw-like magnetic poles as first magneticpoles and set boundary sides coinciding with the circumferential centerpositions of the second claw-like magnetic poles as second magneticpoles. The second magnet sections of the second annular auxiliary magnetare magnetized to set boundary sides coinciding with the circumferentialcenter positions of the first claw-like magnetic poles as first magneticpoles and set boundary sides coinciding with the circumferential centerpositions of the second claw-like magnetic poles as second magneticpoles.

(H) The first magnet sections of the first annular auxiliary magnet aremagnetized to set boundary sides coinciding with the circumferentialcenter positions of the second claw-like magnetic poles as firstmagnetic poles and set boundary sides coinciding with thecircumferential center positions of the first claw-like magnetic polesas second magnetic poles. The second magnet sections of the secondannular auxiliary magnet are magnetized to set boundary sides coincidingwith the circumferential center positions of the second claw-likemagnetic poles as first magnetic poles and set boundary sides coincidingwith the circumferential center positions of the first claw-likemagnetic poles as second magnetic poles.

(I) The first magnet sections of the first annular auxiliary magnet aremagnetized in the axial direction. The second magnet sections of thesecond annular auxiliary magnet are magnetized in the axial direction.

(J) The first annular auxiliary magnet is fixed to the first rotor coresuch that boundaries that divide the first magnet sections respectivelycoincide with circumferential intermediate positions of the firstclaw-like magnetic poles and the second claw-like magnetic poles. Thesecond annular auxiliary magnet is fixed to the second rotor core suchthat boundaries that divide the second magnet sections respectivelycoincide with the circumferential intermediate positions of the firstclaw-like magnetic poles and the second claw-like magnetic poles.

(K) In the rotor, the first magnet sections of the first annularauxiliary magnet opposed to the first claw-like magnetic poles aremagnetized to set the second rotor core sides as first magnetic polesand set first rotor core sides as second magnetic poles in the axialdirection. The first magnet sections opposed to the second claw-likemagnetic poles are magnetized to set the second rotor core sides assecond magnetic poles and set the first rotor core sides as firstmagnetic poles in the axial direction. The second magnet sections of thesecond annular auxiliary magnet opposed to the second claw-like magneticpoles are magnetized to set the second rotor core sides as firstmagnetic poles and set first rotor core sides as second magnetic polesin the axial direction. The second magnet sections opposed to the firstclaw-like magnetic poles are magnetized to set the second rotor coresides as second magnetic poles and set the first rotor core sides asfirst magnetic poles in the axial direction.

(L) In the rotor, the first magnet sections of the first annularauxiliary magnet opposed to the first claw-like magnetic poles aremagnetized to set the second rotor core sides as second magnetic polesand set first rotor core sides as first magnetic poles in the axialdirection. The first magnet sections opposed to the second claw-likemagnetic poles are magnetized to set the second rotor core sides asfirst magnetic poles and set the first rotor core sides as secondmagnetic poles in the axial direction. The second magnet sections of thesecond annular auxiliary magnet opposed to the second claw-like magneticpoles are magnetized to set the second rotor core sides as secondmagnetic poles and set first rotor core sides as first magnetic poles inthe axial direction. The second magnet sections opposed to the firstclaw-like magnetic poles are magnetized to set the second rotor coresides as first magnetic poles and set the first rotor core sides assecond magnetic poles in the axial direction.

(M) A trio of the rotors in the fourth to seventh embodiments arelaminated in the axial direction to form a U-phase rotor, a V-phaserotor, and a W-phase rotor.

(N) A motor including the rotor in the fourth to seventh embodiments.

A rotation detecting method for a motor including the rotor in thefourth to seventh embodiment or the three-phase rotor is provided.

The rotation detecting method includes arranging the magnetic detectorin a position adjacent to at least one annular auxiliary magnet of thefirst annular auxiliary magnet and the second annular auxiliary magnet.The rotation detecting method includes detecting, with the magneticdetector, passage of the magnet sections of the annular auxiliary magnetthat rotates according to rotation of the rotor or the three-phase rotorand detecting rotation of the motor.

What is claimed is:
 1. A motor comprising single motor sections in three stages arranged in order of a first stage, a second stage, and a third stage in an axial direction, each of the single motor sections includes: a rotor section including: a first rotor core including a plurality of claw-like magnetic poles in a circumferential direction; a second rotor core including a plurality of claw-like magnetic poles in the circumferential direction; and a permanent magnet arranged between the first and second rotor cores and magnetized in the axial direction; and a stator section including: a first stator core including a plurality of claw-like magnetic poles in the circumferential direction; a second stator core including a plurality of claw-like magnetic poles in the circumferential direction; and a winding wire arranged between the first and second stator cores and wound around in the circumferential direction, wherein in at least one of the rotor section and the stator section in the single motor section of the second stage, the plurality of claw-like magnetic poles are provided at unequal intervals in the circumferential direction, the permanent magnet in the second stage has a magnetized direction that differs in the axial direction from a magnetized direction of each of the permanent magnets in the first and third stages, a configuration in which the claw-like magnetic poles are arranged at equal intervals in the circumferential direction in the stator section in each of the first to third stages and a phase is shifted by a same angle between the stator sections in the first stage and the second stage and between the stator sections in the second stage and the third stage is referred to as a reference configuration, and the claw-like magnetic poles of the stator section in the second stage are arranged at unequal intervals to increase an overlapping width in the circumferential direction between the claw-like magnetic poles of the stator section in the first stage and the claw-like magnetic poles of the stator section in the second stage with respect to the reference configuration and to increase an overlapping width in the circumferential direction between the claw-like magnetic poles of the stator section in the second stage and the claw-like magnetic poles of the stator section in the third stage with respect to the reference configuration.
 2. A motor comprising single motor sections in three stages arranged in order of a first stage, a second stage, and a third stage in an axial direction, each of the single motor sections includes: a rotor section including: a first rotor core including a plurality of claw-like magnetic poles in a circumferential direction; a second rotor core including a plurality of claw-like magnetic poles in the circumferential direction; and a permanent magnet arranged between the first and second rotor cores and magnetized in the axial direction; and a stator section including: a first stator core including a plurality of claw-like magnetic poles in the circumferential direction; a second stator core including a plurality of claw-like magnetic poles in the circumferential direction; and a winding wire arranged between the first and second stator cores and wound around in the circumferential direction, wherein in at least one of the rotor section and the stator section in the single motor section of the second stage, the plurality of claw-like magnetic poles are provided at unequal intervals in the circumferential direction, the permanent magnet in the second stage has a magnetized direction that differs in the axial direction from a magnetized direction of each of the permanent magnets in the first and third stages, a configuration in which the claw-like magnetic poles are arranged at equal intervals in the circumferential direction in the rotor section in each of the first to third stages and a phase is shifted by a same angle between the rotor sections in the first stage and the second stage and between the rotor sections in the second stage and the third stage is referred to as a reference configuration, and the claw-like magnetic poles of the rotor section in the second stage are arranged at unequal intervals to reduce an overlapping width in the circumferential direction between the claw-like magnetic poles of the rotor section in the first stage and the claw-like magnetic poles of the rotor section in the second stage and to reduce an overlapping width in the circumferential direction between the claw-like magnetic poles of the rotor section in the second stage and the claw-like magnetic poles of the rotor section in the third stage.
 3. A motor comprising single motor sections in three stages arranged in order of a first stage, a second stage, and a third stage in an axial direction, each of the single motor sections includes: a rotor section including: a first rotor core including a plurality of claw-like magnetic poles in a circumferential direction; a second rotor core including a plurality of claw-like magnetic poles in the circumferential direction; and a permanent magnet arranged between the first and second rotor cores and magnetized in the axial direction; and a stator section including: a first stator core including a plurality of claw-like magnetic poles in the circumferential direction; a second stator core including a plurality of claw-like magnetic poles in the circumferential direction; and a winding wire arranged between the first and second stator cores and wound around in the circumferential direction, wherein in at least one of the rotor section and the stator section in the single motor section of the second stage, the plurality of claw-like magnetic poles are provided at unequal intervals in the circumferential direction, the permanent magnet in the second stage has a magnetized direction that differs in the axial direction from a magnetized direction of each of the permanent magnets in the first and third stages, the claw-like magnetic poles of the rotor section in the single motor section in each of the stages include first rotor side claw-like magnetic poles provided at equal intervals in the circumferential direction in the first rotor core and second rotor side claw-like magnetic poles provided at equal intervals in the circumferential direction in the second rotor core, in the single motor sections in the first stage and the third stage, the first and second rotor cores are assembled to alternately arrange the first rotor side claw-like magnetic poles and the second rotor side claw-like magnetic poles at equal intervals in the circumferential direction, and in the single motor section in the second stage, the first and second rotor cores are assembled to alternately arrange the first rotor side claw-like magnetic poles and the second rotor side claw-like magnetic poles at unequal intervals in the circumferential.
 4. The motor according to claim 1, wherein the claw-like magnetic poles of the stator section in the single motor section in each of the stages include first stator side claw-like magnetic poles provided at equal intervals in the circumferential direction in the first stator core and second stator side claw-like magnetic poles provided at equal intervals in the circumferential direction in the second stator core, in the single motor sections in the first stage and the third stage, the first and second rotor cores are assembled to alternately arrange the first stator side claw-like magnetic poles and the second stator side claw-like magnetic poles at equal intervals in the circumferential direction, and in the single motor section in the second stage, the first and second stator cores are assembled to alternately arrange the first stator side claw-like magnetic poles and the second stator side claw-like magnetic poles at unequal intervals in the circumferential direction.
 5. The motor according to claim 2, wherein the claw-like magnetic poles of the stator section in the single motor section in each of the stages include first stator side claw-like magnetic poles provided at equal intervals in the circumferential direction in the first stator core and second stator side claw-like magnetic poles provided at equal intervals in the circumferential direction in the second stator core, in the single motor sections in the first stage and the third stage, the first and second rotor cores are assembled to alternately arrange the first stator side claw-like magnetic poles and the second stator side claw-like magnetic poles at equal intervals in the circumferential direction, and in the single motor section in the second stage, the first and second stator cores are assembled to alternately arrange the first stator side claw-like magnetic poles and the second stator side claw-like magnetic poles at unequal intervals in the circumferential direction.
 6. The motor according to claim 3, wherein the claw-like magnetic poles of the stator section in the single motor section in each of the stages include first stator side claw-like magnetic poles provided at equal intervals in the circumferential direction in the first stator core and second stator side claw-like magnetic poles provided at equal intervals in the circumferential direction in the second stator core, in the single motor sections in the first stage and the third stage, the first and second rotor cores are assembled to alternately arrange the first stator side claw-like magnetic poles and the second stator side claw-like magnetic poles at equal intervals in the circumferential direction, and in the single motor section in the second stage, the first and second stator cores are assembled to alternately arrange the first stator side claw-like magnetic poles and the second stator side claw-like magnetic poles at unequal intervals in the circumferential direction. 